To: Administrative File: CAG-00433N
From: Louis Jacques, MD
Director, Coverage and Analysis Group
Tamara Syrek Jensen, JD
Deputy Director, Coverage and Analysis Group
Jyme Schafer, MD, MPH
Lead Medical Officer
Director, Division of Medical and Surgical Services
Deirdre O’Connor
Lead Health Policy Analyst
Subject: Decision Memorandum for CAG #00433N
Percutaneous Image-guided Lumbar Decompression (PILD) for Lumbar Spinal Stenosis (LSS)
Date: January 9, 2014
I. Decision
A. The Centers for Medicare & Medicaid Services (CMS) has determined that percutaneous image guided lumbar decompression (PILD) for lumbar spinal stenosis (LSS) is not reasonable and necessary under section 1862(a)(1)(A) of the Social Security Act.
B. The CMS has determined that PILD will be covered by Medicare when provided in a clinical study under section 1862(a)(1)(E) through Coverage with Evidence Development (CED) for beneficiaries with LSS who are enrolled in an approved clinical study that meets the criteria below.
CMS has a particular interest in improved beneficiary function and quality of life, specific characteristics that identify patients who may benefit from the procedure, and the duration of benefit. A clinical study seeking Medicare payment for PILD for LSS must address one or more aspects of the following questions in a prospective, randomized, controlled design using current validated and reliable measurement instruments and clinically appropriate comparator treatments, including appropriate medical or surgical interventions or a sham controlled arm, for patients randomized to the non-PILD group.
The study protocol must specify a statistical analysis and a minimum length of patient follow up time that evaluates the effect of beneficiary characteristics on patient health outcomes as well as the duration of benefit.
- Does PILD provide a clinically meaningful improvement of function and/or quality of life in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD provide clinically meaningful reduction in pain in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD affect the overall clinical management of LSS and decision making, including use of other medical treatments or services, compared to other treatments?
These studies must be designed so that the contribution of treatments in addition to the procedure under study are either controlled for or analyzed in such a way as to determine their impact.
- The principal purpose of the research study is to test whether a particular intervention potentially improves the participants’ health outcomes.
- The research study is well supported by available scientific and medical information or it is intended to clarify or establish the health outcomes of interventions already in common clinical use.
- The research study does not unjustifiably duplicate existing studies.
- The research study design is appropriate to answer the research question being asked in the study.
- The research study is sponsored by an organization or individual capable of executing the proposed study successfully.
- The research study is in compliance with all applicable Federal regulations concerning the protection of human subjects found at 45 CFR Part 46. If a study is regulated by the Food and Drug Administration (FDA), it must be in compliance with 21 CFR parts 50 and 56.
- All aspects of the research study are conducted according to appropriate standards of scientific integrity (see http://www.icmje.org).
- The research study has a written protocol that clearly addresses, or incorporates by reference, the standards listed here as Medicare requirements for CED coverage.
- The clinical research study is not designed to exclusively test toxicity or disease pathophysiology in healthy individuals. Trials of all medical technologies measuring therapeutic outcomes as one of the objectives meet this standard only if the disease or condition being studied is life threatening as defined in 21 CFR § 312.81(a) and the patient has no other viable treatment options.
- The clinical research study is registered on the ClinicalTrials.gov website by the principal sponsor/investigator prior to the enrollment of the first study subject.
- The research study protocol specifies the method and timing of public release of all prespecified outcomes to be measured including release of outcomes if outcomes are negative or study is terminated early. The results must be made public within 24 months of the end of data collection. If a report is planned to be published in a peer reviewed journal, then that initial release may be an abstract that meets the requirements of the International Committee of Medical Journal Editors (http://www.icmje.org).
- The research study protocol must explicitly discuss subpopulations affected by the treatment under investigation, particularly traditionally underrepresented groups in clinical studies, how the inclusion and exclusion criteria effect enrollment of these populations, and a plan for the retention and reporting of said populations on the trial. If the inclusion and exclusion criteria are expected to have a negative effect on the recruitment or retention of underrepresented populations, the protocol must discuss why these criteria are necessary.
- The research study protocol explicitly discusses how the results are or are not expected to be generalizable to the Medicare population to infer whether Medicare patients may benefit from the intervention. Separate discussions in the protocol may be necessary for populations eligible for Medicare due to age, disability or Medicaid eligibility.
Consistent with section 1142 of the Social Security Act, the Agency for Healthcare Research and Quality (AHRQ) supports clinical research studies that CMS determines meet the above-listed standards and address the above-listed research questions.
II. Background
The following acronyms are used throughout this document. For the readers convenience they are listed here in alphabetical order.
AANS – American Association of Neurological Surgeons
AAOS - American Association of Orthopaedic Surgeons
AAPM – American Academy of Pain Medicine
AHRQ – Agency for Healthcare Research and Quality
ANOVA - analysis of variance
ASA – American Society of Anesthesiologists
ASIPP – American Society of Interventional Pain Physicians
CED – coverage with evidence development
CNS – Congress of Neurological Surgeons
CT - computed tomography
DM – decision memorandum
DVT - deep vein thrombosis
ESI - epidural steroid injection
HLF – hypertrophic ligamentum flavum
LCD – local coverage determination
LF - ligamentum flavum
LOCF - last observation carried forward
LSS- lumbar spinal stenosis
MIC - minimal important change
MILD - minimally invasive lumbar decompression
MRI - magnetic resonance imaging
NASS - North American Spine Society
NC - neurogenic claudication
NCA – national coverage analysis
NCD - national coverage determination
ODI - Oswestry Disability Index
PDI - Pain Disability Index
PE - pulmonary embolism
PILD - percutaneous image-guided lumbar decompression
PRLL - percutaneous remodeling of ligamentum flavum and lamina
RCT - randomized controlled trial
RMQ - Roland-Morris Disability Questionnaire
VAS - visual analog scale
ZCQ - Zurich Claudication Questionnaire
The scope of this national coverage analysis (NCA) includes a review of the evidence on whether percutaneous image-guided lumbar decompression for LSS provides improved health outcomes in Medicare beneficiaries. This also includes the proprietary procedure mild®.
Most people will experience low back pain at some point in their lives. Pain complaints are the leading reason for medical visits. The most common pain complaints are musculoskeletal, and back pain is the most common of these, and the prevalence and impact of back pain have led to an expanding array of tests and treatments, including injections, surgical procedures, implantable devices, and medications. (Deyo et al. 2009)
Spinal stenosis is the most common reason for lumbar spine surgery in adults over the age of 65 years. (Weinstein et al. 2008) Spinal stenosis often results from the normal aging process. Surgery for spinal stenosis was reported to be the fastest-growing type of lumbar surgery in the United States from 1980 to 2000. Rates of surgery for lumbar stenosis declined slightly from 2002-2007, but use of more complex procedures has increased substantially. (Deyo et al. 2010)
A 1995 population study in Sweden reported spinal stenosis incidence of 50 per 100,000; an incidence of 25 per 100,000 inhabitants for spinal stenosis associated claudication; and, an incidence of 1 per 100,000 for cauda equina syndrome. (ECRI Health Technology Assessment Group. Treatment of Degenerative Lumbar Spinal Stenosis. Rockville (MD): Agency for Healthcare Research and Quality (US); 2001 Jun. (Evidence Reports/Technology Assessments, No. 32.) Available from: http://www.ncbi.nlm.nih.gov/books/NBK33617/)
Lumbar spinal stenosis is defined as the reduction of the cross sectional area, i.e. narrowing, of the lumbar spinal canal. It is usually caused by spinal degenerative conditions and is commonly found to be asymptomatic. (Kovacs et al. 2011) Lumbar spinal stenosis is sub-classified into three broad categories, specifically central stenosis, lateral stenosis, and spondylolisthesis. Central stenosis refers to a narrowing of the spinal canal across the anterioposterior diameter, the transverse diameter, or both.” (ECRI Health Technology Assessment Group. Treatment of Degenerative Lumbar Spinal Stenosis. Rockville (MD): Agency for Healthcare Research and Quality (US); 2001 Jun. (Evidence Reports/Technology Assessments, No. 32.) Available from: http://www.ncbi.nlm.nih.gov/books/NBK33617/)
Symptomatic patients typically present with symptoms of radicular leg pain or with neurogenic claudication (pain in the buttocks or legs on walking or standing that resolves with sitting down or lumbar flexion). Indications for surgery appear to vary widely, and rates of procedures vary five-fold or more across geographic areas. (Weinstein et al. 2008)
The geographic variation in treatment of LSS, the lack of a definitive diagnostic tool, and the absence of reliable evidence about the natural history of the condition bring up issues on how to best approach LSS. The North American Spine Society (NASS) evidence-based clinical guideline identified an absence of reliable evidence about the natural history of degenerative lumbar stenosis. (NASS 2011) The ECRI technology assessment reported, “…the presence of apparent stenosis in the asymptomatic population raises a question about whether stenosis per se causes symptoms, those with more severe symptoms are more likely to have stenosis. …The presence of stenosis and slippage in spinal images of asymptomatic people indicates that treatment must be based on the convergence of symptoms and image evidence rather than on either type of evidence alone.” (ECRI Health Technology Assessment Group. Treatment of Degenerative Lumbar Spinal Stenosis. Rockville (MD): Agency for Healthcare Research and Quality (US); 2001 Jun. (Evidence Reports/Technology Assessments, No. 32.) Available from: http://www.ncbi.nlm.nih.gov/books/NBK33617/)
Haig reported, “Some clinicians use the term stenosis to describe statistical deviation from average size of the spinal canal or neural foramen regardless of the symptoms, while others use it to describe a clinical syndrome that presents classically with neurogenic claudication-pain in the back or legs with ambulation.” (Haig et al. 2006) There are no standard criteria for the clinical diagnosis of stenosis. Anatomic measures can be obtained via imaging tests such as magnetic resonance imaging (MRI), which have become a standard for diagnosis. However no clear relation between the severity of symptoms and the extent of stenosis on imaging exists; and surgical outcomes do not clearly relate to the results of imaging measures. In addition, no cutoff for canal size measurement to diagnose the clinical syndrome has been widely accepted. (Haig et al. 2006)
Little is known about the diagnostic accuracy of the different tests available in detecting lumbar spinal stenosis. (de Graaf et al. 2006) de Graaf talked about an ideal situation with a “clear diagnostic entity with an agreed gold standard to prove its existence as well as knowledge about the natural course and effectiveness of treatments.” (de Graaf et al. 2006) However, there is no consensus about the gold standard. (de Graaf et al. 2006) After a systematic review of the accuracy of diagnostic tests for the diagnosis of LSS, de Graaf could not “draw any firm conclusions about the diagnostic accuracy of imaging, clinical, and other tests in diagnosing lumbar spinal stenosis.” (de Graaf et al. 2006)
It appears consensus as to the definition of spinal stenosis has not been reached among experts. There is no “gold standard” for diagnosis and treatment of stenosis because of variable signs and symptoms, physicians’ history-taking and physical methods and diagnostic tests. (Sandella et al. 2013)
Lumbar spinal stenosis is a pathological condition causing a compression of the contents of the canal, particularly the neural structures. In 2003, Gunzburg and Szpalski opined that if compression does not occur, the canal should be described as narrow but not stenotic. Degenerative disc disease is the most common cause of lumbar spinal stenosis. A bulging degenerated intervertebral disc anteriorly, combined with thickened infolding of ligamenta flava and hypertrophy of the facet joints posteriorly result in narrowing of the spinal canal. The site of compression may be central, lateral or a combination, of the two. “When a canal size is too narrow for the dural sac size that it contains, stenosis occurs. An identical canal size can therefore be stenotic for one person while not being stenotic for another who happens to have a smaller dural sac size. Lumbar spinal stenosis is therefore a clinical condition and not a radiological finding or diagnosis.” (Gunzburg and Szpalski 2003)
The utility of diagnostic imaging studies should be to confirm the information gathered from a thorough history and physical exam. Boden warned, “Excessive reliance on diagnostic studies without precise clinical correlation can lead to erroneous or unindicated treatment of degenerative disorders of the lumbar spine.” (Boden 1996)
The clinical syndrome for stenosis does not always present with classic complaints on examination, and similar symptoms occur in a wide variety of disorders ranging from vascular disease to polyneuropathy to mechanical back pain. Further confusion can come into play when a radiologist report of stenosis influences the clinician’s impression. (Haig et al. 2006) “Because other causes of back pain are both common and difficult to prove, it is possible that mechanical backache, perhaps in conjunction with coincident neuropathy or other unrelated leg complaint, might lead to inappropriate treatment including surgery. Thus accurate diagnosis of the clinical syndrome of spinal stenosis is of critical importance.” (Haig et al. 2006)
“When a patient presents with LSS symptoms and confirmatory imaging, unless they have an absolute indication for surgery (rapidly progressive neurologic decline, clinically relevant motor deficits, or cauda equina syndrome), the treatment algorithm begins with nonoperative management.” (Kurd et al. 2012) Unfortunately, there remains a lack of consensus among clinicians about the indications for surgical intervention for LSS. (Kurd et al. 2012) Non-surgical or conservative care for LSS may include physical therapy, epidural injections, chiropractic manipulation, acupuncture, lumbar corset, the use of anti-inflammatory drugs, and the use of opioid analgesics.
Treatment options for LSS, historically, have varied from conservative management on the one hand and the invasive surgical decompression on the other hand. There is a gap for patients failing the former but not severe enough or not ready for the latter. (Mekhail et al. 2012) “While conservative measures, such as physical therapy with/without epidural steroid injections, may be adequate for mild cases, they fail to provide long-term relief to the moderate-to-severe LSS patient and, thus the progression to the next treatment option of surgery. The goal of surgical treatment for symptomatic lumbar canal stenosis is to achieve relief of symptoms by adequate neural decompression while preserving as much of the anatomy and not disrupting the biomechanics of the lumbar spine as possible.” (Mekhail et al. 2012)
The AAOS website provided the following information about surgical options for LSS.
“Surgery for lumbar spinal stenosis is generally reserved for patients who have poor quality of life due to pain and weakness.” In the past there have been two main surgical options to treat LSS – laminectomy and spinal fusion when there is spinal instability. The laminectomy procedure involves removing the bone and ligaments that are compressing the nerves. The traditional laminectomy procedure has been performed as an open procedure however a laminectomy can also be done using a minimally invasive method. These newer, minimally invasive decompression procedures are performed using smaller incisions and surgeons rely more on microscopes to see the area of surgery. Another minimally invasive procedure is the placement of an interspinous process device which involves placing a spacer between the spinous process in the back of the spine to keep the space for the nerves open by spreading the vertebrae apart.” (AAOS website http://orthoinfo.aaos.org/topic.cfm?topic=a00329)
The focus of this national coverage analysis is on a newer technique - percutaneous image-guided lumbar decompression (PILD) which is a posterior decompression of the lumbar spine performed under indirect image guidance without any direct visualization of the surgical area. The use of a cannula and trocar provides a portal that allows access to the anatomic area for instruments used forresection. This is a procedure proposed as a treatment for symptomatic LSS unresponsive to conservative therapy. This procedure is generally described as a relatively non-invasive (compared to open surgery) procedure using specially designed instruments to percutaneously remove a portion of the lamina and debulk the ligamentum flavum. (The terms non-invasive, minimally invasive and percutaneous are used interchangeably in the literature.) The procedure is performed under x-ray guidance (e.g., fluoroscopic, CT) with the assistance of contrast media to identify and monitor the compressed area via epidurogram. The procedure that most closely falls under this description is commercially known as the mild® procedure. (Vertos Medical)
“The mild procedure offers a minimally invasive alternative to a standard laminotomy-laminectomy." (Deer et al. 2011)
Endoscopically assisted laminotomy/laminectomy, which requires open and direct visualization, as well as other open lumbar decompression procedures for LSS are not within the scope of this NCA.
III. History of Medicare Coverage
CMS does not currently have an NCD on PILD.
A. Current Consideration
CMS internally decided to open this national coverage analysis (NCA) to thoroughly review the evidence on whether the PILD procedure provided improved health outcomes in Medicare beneficiaries with symptomatic LSS.
B. Benefit Category
Medicare is a defined benefit program. An item or service must fall within a benefit category as a prerequisite to Medicare coverage. An item or service must meet one of the statutorily defined benefit categories in the Social Security Act and not otherwise be excluded. PILD may be considered to be within the benefits described under sections;
- 1861(b) as an inpatient hospital service,
- 1861(s)(2)(B) as a hospital service incident to physicians’ services rendered to outpatients, and
- 1861(s)(1) as a physician service.
Note: This may not be an exhaustive list of all applicable Medicare benefit categories for this item or service.
IV. Timeline of Recent Activities
| Date |
Action |
| 04/05/2013 |
CMS initiates this national coverage analysis. Initial comment period opens. |
| 05/03/2013 |
Meeting with representatives from Vertos. |
| 05/05/2013 |
Initial public comment period closes. |
| 08/08/2013 |
Meeting with representatives from Vertos. |
| 10/17/2013 |
Proposed decision memorandum posted and second comment period opens. |
| 11/16/2013 |
Second public comment period closes. |
V. Food and Drug Administration (FDA) Status
Various devices implanted during spine surgery may fall under the FDA regulatory oversight. The focus of our review is for the PILD procedure and no devices are implanted during this procedure, however there are specialized instruments that are used which are under the oversight of the FDA.
The mild® tool kit (Vertos Medical) initially received 510(k) clearance as the X-Sten MILD Tool KIT (X-Stern Corp.) in 2006. The indications for use are identified as, “The X-Sten MILD Tool Kit™ is a set of specialized surgical instruments intended to be used to perform percutaneous lumbar decompressive procedures for the treatment of various spinal conditions.” (http://www.accessdata.fda.gov/cdrh_docs/pdf6/K062038.pdf)
The totalis™ instrumentation system (VertiFlex) received 510(k) clearance as VertiFlex Direct Decompression System in 2012. The indications for use are identified as, “The VertiFlex® Direct Decompression System is a set of specialized surgical instruments intended to be used to perform lumbar decompressive procedures for the treatment of various spinal conditions.” (http://www.accessdata.fda.gov/cdrh_docs/pdf12/K122662.pdf)
VI. General Methodological Principles
When making national coverage decisions under §1862(a)(1)(A), CMS generally evaluates relevant clinical evidence to determine whether or not the evidence is of sufficient quality to support a conclusion that an item or service falling within a benefit category is reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member. The critical appraisal of the evidence enables us to determine to what degree we are confident that: 1) the specific assessment questions can be answered conclusively; and 2) the ntervention will improve health outcomes for patients. An improved health outcome is one of several considerations in determining whether an item or service is reasonable and necessary.
A detailed account of the methodological principles of study design that the agency utilizes to assess the relevant literature on a therapeutic or diagnostic item or service for specific conditions can be found in Appendix A. In general, features of clinical studies that improve quality and decrease bias include the selection of a clinically relevant cohort, the consistent use of a single good reference standard, and the blinding of readers of the index test, and reference test results.
Public comments sometimes cite the published clinical evidence and give CMS useful information. Public comments that give information on unpublished evidence such as the results of individual practitioners or patients are less rigorous and therefore less useful for making a coverage determination. Public comments that contain personal health information (PHI) will be redacted and the PHI will not be made available to the public. CMS uses the initial public comments to inform its proposed decision. CMS responds in detail to the public comments on a proposed decision when issuing the final decision memorandum.
VII. Evidence
A. Introduction
Assessment of outcomes for symptomatic degenerative lumbar spinal stenosis
Neurogenic claudication and various back and leg pains are symptoms. Sustained improvement in these symptoms of pain perception and a reduction in the pain-related functional restrictions are appropriate outcomes of clinical trials. It is challenging to attribute symptom changes to treatment because the natural history of degenerative lumbar spinal stenosis is unclear. (Issack 2012) Additionally, pain perception is subject to regression to the mean and the placebo effect. Therefore, clinical trials with appropriate controls utilizing independently assessed validated instruments are most heavily weighted.
Patient reported outcomes reflecting symptoms and function are often used to measure the effects of treatment for symptomatic degenerative lumbar spinal stenosis. Standardizing the measures facilitates study comparison. The most commonly used instruments are the Oswestry Disability Index (ODI) and the visual analog scale (VAS). The ODI is used to measure a patient’s functional disability on a scale of 1 to 100. VAS measures pain intensity on a scale of 0 to 10. The Zurich Claudication Questionnaire (ZCQ) is a less commonly used assessment tool for patient function and has several domains. The Pain Disability Index (PDI) and the Roland-Morris Disability Questionnaire (RMQ) are also tools for measuring disability. The SF-36 and shorter version, SF-12, are measures of general health status. A recent study in patients with LSS revealed that subjective measures of pain and disability had little correlation to actual patient activity, calling into question the current use of these measures without other performance or non-pathology specific outcomes. (Pryce et al. 2012) CMS attributes more evidentiary weight to those studies reporting reliable, validated outcomes that reflect true patient activity and quality of life.
With the use of any of these instruments, consideration must be given to the clinical meaning of a change in the reported score. How well, if at all, does a score change of some increment reflect a meaningful change in symptom or function experienced by the patient? Other considerations include the error of measurement of the instrument used and the clinical importance of a statistically significant score change. In a 2003 study by Hagg of 289 patients treated surgically or non-surgically in a randomized controlled trial, the standard error of measurement of the ODI was four units, with a 95% tolerance interval of 10, and the minimum difference that appeared clinically important was 10 units. The minimal clinically important difference of VAS back pain was 18-19 units [on a 100 point scale] with a 95% tolerance interval of 1.5. (Hagg et al. 2003) These recommendations are similar to those by Ostelo who also noted that when baseline was taken into account a 30% improvement, when comparing before and after measures for individual patients, should be the guide for the minimal important change (MIC). (Ostelo et al. 2008) Ostelo, in an aim towards international consensus regarding minimal important change, noted that workshop participants (during the Low Back Pain Forum VIII) stressed that proposed MIC values were for individual rather than group changes. (Ostelo et al. 2008) The clinically important change is based on an individual, but is often misused to compare the difference in mean scores between two groups, but this is not a clinically important difference. (MEDCAC 2006)
Determining the true clinical impact of interventions that treat pain and improve pain related functional difficulties is challenging. Well-designed clinical trials can provide the strongest evidence for treatment effect. Well-constructed randomization protects against bias and inclusion of an appropriate comparator facilitates study interpretation. In pain treatment trials, the natural history of the disease, regression toward the mean and the placebo response are important considerations. For these reasons, an appropriate comparator is necessary for accurate interpretation. Accurate interpretation of pain treatment trials also necessitates reporting of concomitant pain treatments, most importantly analgesic use. In the case of research in the area of pain treatment, more evidentiary weight is accorded to studies that are designed to mitigate the bias of placebo response and that account for the natural history of the disease and regression toward the mean.
B. Literature Search
CMS performed a literature search on 5/3/2013 utilizing PubMed for randomized controlled trials (RCTs) and nonrandomized controlled trials, cohort or case-control studies, case series studies and systemic reviews for “percutaneous image-guided lumbar decompression for lumbar spinal stenosis.” The literature search was limited to the English language and specific to the human population, but included studies conducted in all countries, including the United States. This literature search was updated on 11/29/2013 and no new studies were identified.
Evidence for percutaneous image-guided lumbar decompression for lumbar spinal stenosis comes from the mild® literature and includes one randomized study, seven case series, one meta-analysis and one systematic review. Single site reports of larger reported studies were reviewed but not listed in the evidence section of this DM so as to not duplicate patient reporting. Studies with ten patients or less were reviewed but not listed in the evidence section. Studies identified as follow-up studies from earlier studies were listed together.
C. Discussion of Evidence Reviewed
1. Question:
The question of interest for this NCA is:
Is the evidence sufficient to conclude that PILD improves health outcomes in Medicare beneficiaries with lumbar spinal stenosis?
Health outcomes of greatest interest include significant pain relief and improved function in day-to-day activities.
2. External technology assessment (TA)
An external TA was not commissioned.
3. Internal technology assessment
Lingreen R, Grider S. Retrospective review of patient self-reported improvement and post-procedure findings for mild® (minimally invasive lumbar decompression). Pain Physician 2010; 13:555-560.
Lingreen and Grider reported on 42 consecutive patients ages 52 – 86 “meeting magnetic resonance imaging (MRI) criteria” who underwent the procedure performed by two pain management physicians at the same clinic. The aim of the study was to “fill important gaps in this emerging body of literature concerning Minimally Invasive Lumbar Decompression or mild.” The inclusion criteria were spinal stenosis and ligamentum flavum hypertrophy on MRI; no details were provided. All patients had undergone previous conservative treatment including lumbar epidural steroid injections, opioid and non-opioid medication and physical therapy. Patient reported VAS, ADLs, opioid use, patient satisfaction and complication data were collected. Patients were contacted on post-procedure days three, seven and 14.
No major adverse events were reported. Five of 42 patients required post-procedure opioids. A survey was done at some point and 36 or 42 (86%) of patients reported that they would recommend the mild procedure to others. The VAS pre- and 30 day post-procedure were reported as 9.6 ± 0.42 and 5.8 ± 2.5, with the difference being p < 0.05. Pre-procedure only one patient reported he could walk greater than 15 minutes, while 25 reported this 30 days post-procedure. For standing greater than 15 minutes, six could do so pre-procedure and 31 post-procedure.
The authors noted, “At present there are no clear-cut standards as to what constitutes radiologic spinal stenosis, much less ligamentum flavum hypertrophy.” While ligamentum hypertrophy is one of two inclusion criteria, the authors noted, “The lack of documented ligamentum flavum thickening for each patient is a drawback to the current study. Future studies could attempt to standardize the selection criteria of patients for this procedure with vigorous determination of ligamentum flavum thickness perhaps better predicting who will benefit from the procedure.”
The authors concluded, “The results of the current study suggest that minor adverse events with mild consist mainly of soreness at the procedure site which is self-limiting, infrequently requiring additional procedures or even post-procedure opioid as an intervention. In keeping with other reports, the procedure appears to offer a safe and effective alternative to patients suffering from LSS. Clearly prospective, randomized trials comparing safety and efficacy of mild to other established treatments for spinal stenosis will be necessary.”
Schomer DF, Solsberg D, Wong W, Chopko BW. mild® Lumbar decompression for the treatment of lumbar spinal stenosis. The Neuroradiology Journal 2011; 24:620-626.
The purpose of this report is “to present a meta-analysis of acute safety and three-month clinical outcomes of over 250 mild patients.” Demographics were available on 163 patients, acute safety on 253 patients, and VAS and ODI on 107 patients. The patients in the study were treated from January, 2008 through July, 2010, and patient information appeared to come from a variety of sources. The study included patients with IRB approval and patient consent as well as retrospective surveys of “case procedural notes where IRB approval was not required or obtained.” Mean age was 68.8 years and with 40.5% were male. Patients with both unilateral and bilateral treatments were included. There were no reports of major complications, defined as dural tears, nerve root injury, post-op infection, hemodynamic instability, and post-op spinal structural instability. VAS was 7.4 at baseline with a three-month follow-up of 3.9, p < 0.0001 using a t-test for correlated samples. ODI at baseline was 48.0 with a three month follow-up of 30.9, p < 0.0001 using the t-test for correlated samples. No ranges were given for baseline or follow-up measurements. Comparisons were made to the surgical cohort in the SPORT trial. The authors concluded, “As a less-invasive alternative to decompression surgery, mild Lumbar Decompression has demonstrated comparable patient outcomes to standard decompressive laminectomy, with shorter procedure times, less blood loss, shorter hospital stays, and significantly better safety.”
Chopko BW. A novel method for treatment of lumbar spinal stenosis in high-risk surgical candidates: pilot study experience with percutaneous remodeling of ligamentum flavum and lamina. J Neurosurg Spine 2011; 14;46 - 50.
Chopko reported initial experience in the application of the PRLL technique to a patient population in which medical comorbidities placed the patients into a high-risk stratification with regard to open surgical decompression. PRLL stands for percutaneous remodeling of ligamentum flavum and lamina. Age ranged from 44 to 84, with unilateral and bilateral treatments in the lumbar spine, some with multiple levels. Dates of treatment ranged from April, 2008 to May, 2009. BMI ranged from 19.9 to 44.3. Comorbidities included diabetes, hypertension, muscular dystrophy, and cancer with metastasis.
During the procedure, patients received both local anesthesia (18.5 ml of 1% lidocaine and 11.8 ml of 0.5% bupivacaine) and minimal intravenous sedation and analgesia. The author stated, “In a typical case, the instruments are used to resect between 20 and 50 fragments of bone and ligamentous tissue per single hemilaminar segment, with each tissue fragment measuring between 0.5 and 3.0 mm in greater dimension. A relative flattening of the epidural contrast layer, combined with less restricted flow of contrast, are used as factors to determine when to conclude the decompression.”
Twelve of 14 patients reported a statistically significant improvement in VAS score (preoperative average score of 7.61 ± 2, postoperative average score of 3.61 ± 2.9). ODI change was not statistically significant. Patient follow-up ranged from 4 to 72 weeks. Two patients had postoperative complications, one with a deep vein thrombosis (DVT) and pulmonary embolism (PE), another with an incarcerated small bowel herniation where the patient underwent urgent bowel resection and colostomy followed by an eight-week hospitalization. Another patient had a laminectomy due to continued decline. An additional three patients died during the postoperative observation period from unrelated conditions. Of 11 patients receiving narcotics preoperatively, six had either reduced or eliminated narcotic usage by the time of final postoperative evaluation.
The author stated, “The weaknesses of the present study are many, including the lack of a control group and the variability of follow-up periods.” In addition, the author stated, “Although the precise mechanism of action is not addressed in this clinical study, potential mechanisms may include a reduction in the dorsal-to-ventral directed tension within a pathologically “buckled” ligament, as well as an overall increase in the cross-sectional diameter of the spinal canal. In essence, the PRLL strategy is an investigation into the minimum amount of ligamentous resection that is sufficient to achieve a positive clinical effect. Neuroimaging studies and measurements of intraligament pressures before and after a PRLL procedure may shed some light on the basic mechanism of the pain reduction.” The author concluded, “The PRLL procedure, although clearly not equivalent to an open decompressive procedure, nevertheless had a moderate effect on pain reduction, as evidenced by this small pilot study.”
The author acknowledged, “A future study to include a substantial expansion in patient population as well as uniform long-term follow-up will be critical to a better understanding of the ultimate role of the PRLL strategy.”
Deer TR, Kim C K, Bowman II RG, Ranson MT, Yee BS. Study of percutaneous lumbar decompression and treatment algorithm for patients suffering from neurogenic claudication. Pain Physician 2012; 15:451-460.
The authors stated, “The goal of this study was to evaluate the safety and outcome of symptomatic LSS patients treated with mild percutaneous lumbar decompression (Vertos Medical, Aliso Viejo, CA).” Forty-six patients were enrolled from a single center between March 2010 and January 2011, with a mean age of 66.1 (range 46 to 80). Thirty-four patients (74%) had been under medical management for over 6 months; three patients (7%) for three to six months; and nine patients (20%) under medical management for less than three months. The author stated, “…43 patients (93%) suffered from facet hypertrophy, and 41 patients (89%) suffered from a bulging disc.” Inclusion criteria were, “adult LSS patients suffering from NC [neurogenic claudication] primarily caused by ligamentum flavum (LF) hypertrophy, although the presence of other less predominant contributing factors was not exclusionary. Preoperative magnetic resonance (MRI) or computed tomography (CT) provided radiologic evidence of hypertrophic LF > 2.5 mm, as well as a clearly reduced central canal cross-sectional area.” Patients had to walk at least 10 feet unaided before being limited by pain and must have failed conservative therapy, which was not defined. Patients were also excluded if they “suffered from severe back or leg pain from causes other than LSS,” recent spinal fracture or prior surgery at treatment level, if “disc protrusion or facet hypertrophy were deemed severe enough to potentially confound study outcomes,” used non-steroidal anti-inflammatory drugs within 5 days, or had an epidural steroid injection within three weeks prior to the study.
The VAS, ODI, and ZCQ were assessed at baseline, 12 weeks, six months, and one-year. Safety was monitored. Serious adverse events were defined as blood loss requiring transfusion, nerve injury, epidural bleeding or hematoma, dural puncture or tear, or “any other device or procedure-related significant complications.” For data, missing value imputations were performed using the last-observation-carried-forward (LOCF) method. No data tables were provided. Patients underwent the procedure at various levels. Fluoroscopy time ranged from 38 to 279 seconds. The authors stated there were no major device or procedure-related complications. The authors reported that data were available for 35 of 46 patients for all follow-up periods.
For this group of 35 patients the VAS difference from baseline was statistically significant from a mean of 6.9 (95% CI ± 0.6) at baseline to a mean of 4.2 (95% CI ± 1.0) at 12 weeks, a mean of 4.4(95% CI ± 1.0) at six months, and a mean of 4.0 (95% CI ± 1.0) at one year. For this group of patients the ODI difference from baseline was statistically significant from a mean of 49.4 (95% CI ± 2.5) at baseline to a mean of 35.1 (95% CI ± 5.6) at 12 weeks, a mean of 35.0 (95% CI ± 5.5) at 6 months, and a mean of 32.0 (95% CI ± 5.8) at one year. ZCQ was analyzed for 34 patients and the authors reported a statistically significant improvement in all ZCQ domains. Of 11 patients missing data and not included in the reported outcomes, one had a fusion and one had a laminectomy and were not included in the 35 patients that were reported. Pre and post-procedure medications were not reported. It was not mentioned if there were any additional procedures other than the two back surgeries. Any additional therapies such as physical therapy were not reported. Patient comorbidities were not reported. The authors concluded, “In this study, the mild procedure was shown to be safe, with properly diagnosed patents experiencing significant improvement in mobility and significant reduction of pain at one year after the procedure.”
Wong W. mild interlaminar decompression for the treatment of lumbar spinal stenosis, procedure description and case series with 1-year follow-up. Clin J Pain 2012; 28:534-538.
The author reported on 17 patients treated between April, 2008 and August, 2009 at five different sites. The mean age was 73.1 years (range 63 to 86). The author stated all patients had previously failed conservative therapy. No details were provided. The author noted, “In our practice, the mild procedure is complete when we are no longer able to readily remove further ligamentum flavum, and a repeat epidurogram shows considerable improvement in flow of contrast across the stenotic segment.” He further added, “Volumetric measurements of removed tissues are not collected, primarily because of the fact that only a very small amount is removed during the procedure and quantification is problematic.” Baseline VAS was 7.6 and was 2.3 at one-year follow-up. Average baseline ODI decreased from 48.4 to 21.7 at 1-year. No details were provided on any other pre or post procedure treatments or comorbidities. The author concluded, “This clinical outcome assessment demonstrates that, for this patient series, the mild procedure provided significant pain relief at 1-year posttreatment and increased mobility for patients with symptomatic LSS.”
Brown LL. A double-blind, randomized, prospective study of epidural steroid injection vs. the mild® procedure in patients with symptomatic lumbar spinal stenosis. Pain Practice 2012, 12:333-341.
Brown reported on 38 patients in a double-blind, randomized study of the mild procedure and epidural steroid injections (ESI) at a single site, 21 in the mild group and 17 in the ESI group. Fifty patients were screened and 38 patients were enrolled. Inclusion criteria were 18 years old at minimum, previously failed conservative therapy, ODI > 20, radiologic evidence of L3-L5 LSS, ligamentum flavum > 2.5 by MRI or CT, central canal cross sectional area ≤ 100mm², anterior listhesis confirmed to be ≤ 5.0 mm, and ability to walk at least 10 feet unaided. Exclusion criteria included prior surgery at the intended treatment level or had previously been treated with epidural steroids, recent spinal fractures, disabling back or leg pain from causes other than LSS, fixed spondylolisthesis > Grade 1, disk protrusion or osteophyte formation, excessive facet hypertrophy, bleeding disorders, current use of anticoagulants, would healing pathologies deemed to compromise outcomes such as diabetes, cancer, severe COPD, ASA or NSAID within five days of treatment, pregnancy, inability to lie prone for any reason, inability to give informed consent, on Workman’s compensation, and considering litigation associated with the back pain.
Patients were randomized in blocks of four. Patients randomized to ESI received 80mg of triamcinolone acetate (40 mg in diabetic patients). All patients were followed postoperatively by an independent third party. Patients were unblinded at six weeks and cross-over was offered. The primary endpoint was VAS. Other measures included ODI and ZCQ. Mean age in the mild group was 74.2 (range 51 to 89), with a mean age of 78.7 (range 64 to 89) in the ESI group. Sixty-two percent of the mild patients were male and 47% of the ESI patients were male. The pre-procedure duration of medical management ranged from less than one month (four in the mild group and two in the ESI group) to greater than six months (13 in each group). Patients in the mild group underwent 68 procedures, 33 levels bilaterally and two levels unilaterally, whereas patients in the ESI group had only one injection, even though “…there is no consensus among interventional pain management specialists regarding type, dosage, frequency, approach, and total number of injections in ESI therapy, generally multiple injections are administered at various intervals.” Patients in both groups were discharged on the same day on their procedures.
The author reported that 16 of 21 mild patients experienced a two-point or greater improvement in VAS at six weeks, versus only six of 17 ESI patients. Patients in the mild group improved from an average VAS baseline of 6.3 (95% CI ± 0.7) to a mean of 3.8 (95% CI ± 1.3) at six week follow up. Patients in the ESI group had a mean of 6.4 (95% CI ± 1.0) at baseline compared with 6.3 (95% CI ± 1.4) at six-week follow-up. For ODI, patients in the mild group had a decrease from a baseline mean ODI from 38.8 (95% CI ± 4.2) to 27.4 (95% CI ± 7.0) at six week follow-up, and in the ESI group the baseline ODI was 40.5 (95% CI ± 5.9) and six week follow-up ODI of 34.8 (95% CI of ± 8.2). The change in VAS and ODI in the mild group from week six to 12 was not significant. The ESI group was not measured at week 12. The ZCQ difference between groups was not significant at week six. Many patients in the ESI group crossed-over before 12 weeks. Eventually, all ESI patients had the mild procedure performed. For 14 of these 17 patients in the cross-over ESI group, their baseline VAS was 7.4 (95% CI ± 0.98) with improvement to a mean of 4.5 (95% CI ± 1.46) after mild. Comorbidities, pain medications, and other relevant therapies were not reported. Adequacy of blinding was not reported.
The author concluded, “The findings from this double-blind, randomized, prospective study of ESI vs. the mild procedure in the treatment of LSS patients suffering from symptomatic neurogenic claudication indicate that mild provides statistically significantly better pain reduction and improved functional mobility vs. treatment with ESI.”
Deer TR and Kapural L. New Image-guided ultra-minimally invasive lumbar decompression method: the mild® procedure. Pain Physician 2010; 13:35-41.
A chart review was conducted by 14 physicians on 90 patients from 12 medical centers January 2008 through July 2009. The authors stated, “This technical survey was conducted to assess any significant issues with the procedure’s safety profile.” Factors evaluated were incidence of dural puncture or tear, blood transfusion, nerve injury, and epidural bleeding or hematoma. “To be included in the study, the procedural record was reviewed for content including age, gender, etiology of spinal stenosis (specifically hypertrophic ligamentum flavum), and complete notes stating any procedural difficulties, pre-procedural neurological status, and baseline co-morbidities.” None of the procedures resulted in what the authors defined as adverse events occurring during or immediately following the procedure prior to discharge. The authors concluded, “This review demonstrates the acute safety of the mild procedure with no report of significant or unusual patient complications.”
Mekhail N, Costandi S, Abraham B, Samuel SW. Functional and patient-reported outcomes in symptomatic lumbar spinal stenosis following percutaneous decompression. Pain Practice 2012; 12: 417-425.
The authors stated, “The goal of this study was to report changes in the functional abilities and pain relief for the first 40 consecutive LSS study patients treated with mild percutaneous lumbar decompression at the Pain Management Department of the Cleveland Clinic.” Study inclusion criteria included neurogenic claudication, radiographic T2-weighted MRI-confirmed LF hypertrophy ≥ 4.0 mm, failure of conservative treatment, ability to walk at least 10 feet unaided before being limited by pain. Patients were excluded if they had prior surgery at the treatment level and/or significant radicular leg pain not attributed to LSS, use of anticoagulants, NSAIDs within 7 days, ESIs within 4weeks prior to the procedure, and mobile or greater than Grade 1 spondylolisthesis. Patients were treated September 2010 through August 2011.
Age ranged from 53 to 86, with a mean of 72.2 years, with 62.5% female. “On average, patients had endured painful neurogenic claudication for 5 years prior to study enrollments, and 8 patients had symptoms for over 10 years.” Co-morbidities that were mentioned include radicular pain and osteoarthritis of the knee (five patients), sacroiliac (four patients), and hip (three patients), and cardiac disease (three patients). The authors stated that the mean pretreatment LF thickness was 7.1 mm, no post treatment measurement was reported. Patients underwent procedures at one and two levels, unilaterally and bilaterally. Outcomes include the Pain Disability Index (PDI), the Roland-Morris Disability Questionnaire (RMQ), standing time and walking distance prior to experiencing symptoms, and VAS for pain. These measures were evaluated at baseline and again at four postoperative visits that ranged from three months post-op to one year. The last reported visit was recorded as the one year visit. Safety data were collected at the time of treatment and at follow-up visits. Statistical tests included analysis of variance (ANOVA) with repeated measures and the post-hoc Tukey HSD test.
The authors reported that there were no reports of device or procedure related serious adverse events at the time of the procedure and at any point during the follow-up. “Six patients have not yet been seen for the 1-year visit, but are included in posttreatment analyses prior to 1 year. Two of these 6 patients underwent subsequent spine surgery during the 1-year follow-up period and were discontinued from the study. Both patients, although improved after the mild procedure, chose to undergo additional back surgery (1with fusion and the other with discectomy) to address ongoing radicular pain. The remaining 34 patients were available for all follow-up periods and comprise the cohort population.” For the 34 patients, the reported measures showed improvement. The intention to treat population (ITT) included all 40 patients. The PDI cohort had a statistically significant improvement from a mean of 41.4 (95% CI ± 4.6) at baseline to an average of 18.8 (95% CI ± 4.9) at one-year, with each interim follow-up also statistically significant. The RMQ study cohort baseline average of 14.3 (95% CI ± 2.1) improved at one year to a mean of 6.6 (95% CI ± 2.0), with each interim measure statistically significant from baseline. Standing time improved from a baseline of eight minutes to 56 minutes at 12 month follow-up, with walking distance improving from a baseline mean of 246 feet to 3,956 feet at month 12. VAS for the cohort improved from 7.1 (95% CI ± 0.8) to 3.6 (95% CI ± 0.9) at 12 months for the 34 patients. The authors stated that the 1-year ITT analysis of PDI, RMQ, standing time, walking distance, and VAS were statistically significant (ANOVA, p < 0.0001). Additional therapies or change in therapies both pre and post procedure were not reported.
The authors concluded, “This study demonstrated significant functional improvement as well as decreased disability secondary to neurogenic claudication at 1 year following percutaneous lumbar decompression.”
Chopko B and Caraway DL. MIDAS 1 (mild® decompression alternative to open surgery): a preliminary report of a prospective, multi-center clinical study. Pain Physician 2010; 13:369-378.
Mekhail N, Vallejo R, Coleman MH. Benyamin Ramsin M.; Long-term results of percutaneous lumbar decompression mild® for spinal stenosis. Pain Practice 2012; 12(6):184-193.
Chopko B. Long-term results of percutaneous lumbar decompression for LSS, two-year outcomes. Clin J Pain 2013;
The above three articles report six week (Chopko et al. 2010), one year (Mekhail et al. 2012), and two year (Chopko 2013) follow-up for the observational trial listed as NCT00956631 in clinical trials.gov. Chopko (2010) stated, “The study was conducted by 14 US spine specialists from July 2008 through January 2010.” Seventy-eight patients entered the study. Inclusion criteria were symptomatic LSS primarily caused by dorsal element hypertrophy, prior failure of conservative therapy, radiologic evidence of LSS, hypertrophic LF > 2.5 mm, central canal sectional area ≤ 100 square mm, anterior listhesis ≤ 5mm, and ability to walk at least 10 feet unaided before being limited by pain.
Additional criteria included availability to complete follow-up and ability to provide informed consent. Conservative therapy was not defined. Exclusion criteria included prior surgery at the treatment level, history of recent spinal fractures with pain symptoms, disabling back or leg pain from causes other than LSS, significant/symptomatic disc protrusion or osteophyte formation, excessive/symptomatic facet hypertrophy, bleeding disorders or current use of anticoagulants, use of ASA or NSAID within five days of treatment, epidural steroids within prior 3 weeks, potential wound healing pathologies, dementia, pregnancy, Worker’s Compensation, and considering litigation associated with the pain. The authors also stated, “Although patients who also had foraminal stenosis and lateral recess stenosis were not excluded, the target patient population was those with lumbar central canal stenosis with hypertrophic LF as a contributing factor.” Outcomes were assessed with VAS, ODI, ZCQ, and the SF-12V2®. Reported patient demographics on 75 patients included an age range from 37 years old to 88 years with an average of 70.0 years and 61.3% female. Other demographics and baseline information such as comorbidities and duration of back pain or previous treatments was not reported.
Fifty-one percent of patients were treated at two levels, one patient was treated at three levels, and of the 115 total treated levels, 11 were treated unilaterally. At six weeks, the authors reported no major device or procedure-related complications, with major complications defined as dural tears, nerve root injury, post-op infection, hemodynamic instability, and post-op spinal structural instability. The authors stated that minor complications were not tracked. For 75 patients, the average baseline VAS was 7.3 (range three to 10), and the six-week follow-up average was 3.7 (range 0 to 10) with a statistically significant difference using t-test for correlated samples. For 75 patients, the average baseline ODI was 47.4 (range 16 to 84), and the six-week follow-up was 29.5 (range 0 to 72) with a statistically significant difference using t-test for correlated samples. For the ZCQ components, between 61 and 67 patients had reported outcomes. Sixty two patients had reported scores for ZCQ overall symptom severity, with a pre-treatment mean score of 3.69 (range 1.57 to 5) and post-treatment mean score of 2.35 (range one to 4.57). For ZCQ physical function domain, 61 patients had a pre-treatment mean of 2.67 (range of one to four), with a post-treatment score of 1.96 (range of one to 3.20). Sixty-seven patients reported the SF-12V2. The results are shown in a bar graph and the authors reported, “The patients’ health status was improved for the two summary surveys (PCS and MCS) and all 8 survey scales as compared to baseline.” They further said, “This improvement is statistically significant (95%CI) for all but the General Health (GH) survey scale.” The use of any additional therapies such as pain medication or physical therapy was not reported.
The authors concluded, “In this 75-patient MiDAS I trial, and in keeping with a previously published 90-patient safety cohort, the mild procedure proved to be safe. Further, based on near-term follow-up, the mild procedure demonstrated efficacy in improving mobility and reduced pain associated with lumbar spinal canal stenosis.”
The one year follow-up (Mekhail et al. 2011) was reported from 11 US sites with a cohort of 58 patients who had undergone 170 procedures. At one year, there was no major device or procedure-related complications. Of the 58 patients reported, 44 had conservative medical management for symptomatic LSS for more than six months before the procedure, while 12 had conservative medical management for six months or less. For two patients this was not reported. The authors added: “Sairyo et al. reported average thickness of ligamentum flavum in non LSS patients to be 2.44 mm. This was based on 308 measurements in 77 patients at various ligamentum flavum levels via magnetic resonance imaging (MRI). This finding was used to determine 2.5mm as the minimum starting point for patient entry into the study.” It was acknowledged that patients may have a number of other structural factors such as foraminal stenosis and lateral recess stenosis, so the study was not designed to exclude these factors. The treating physician was ultimately responsible for determining which patients would be best suited for percutaneous laminotomy with ligamentum flavum resection.
The authors explained one of the inclusion/exclusion criteria, “To accomplish true baseline recordings for this patient population, it was determined that patients should be free of steroid injections within the prior 3 weeks of baseline.” Patient success at one year was determined if the patient experienced a two-point improvement in VAS, with secondary outcomes being: the procedure was completed as planned; the patient had a decrease in ODI; the patient did not have a significant device or procedure related adverse effect; and, no re-operation. For analytic purposes, mean change from baseline was assessed for VAS, ODI, ZCQ, and SF-12V2 using the paired t-test. It was noted that half of the 58 patients had an overnight hospital stay associated with the initial procedure.
For these 58 patients, VAS at one year follow-up was an average of 4.5 (95% CI ± 0.8), a statistically significant difference from baseline. ODI average at one year was 36.7 (95% CI ± 5.8), a statistically significant difference from baseline. ZCQ overall symptom severity score at one-year was 2.88 (95% CI ± 0.34) for 51 patients. ZCQ physical function domain score for 49 patients was 2.19 (95% CI ± 5.8), a statistically significant difference from baseline. For the SF-12V2, 58 patients were included in the analysis that was done by component. The physical component summary mean improvement at one-year was statistically significant, and the mental component summary mean improvement was not. Any additional therapies such as pain medication, injections, or physical therapy were not reported. The authors stated, “The authors plan continued follow-up of ongoing RCTs comparing mild with a series of epidural steroid injections.” The authors concluded, “In this 58-patient 1-year cohort, the mild procedure proved to be safe. In addition, at 1-year follow-up mild demonstrated efficacy by significantly improving mobility and reducing pain associated with lumbar spinal stenosis.”
Chopko 2013 reported on the two-year follow-up for 45 patients at 11 US sites. Outcome measures reported included VAS, ODI, and ZCQ. Thirteen of the 58 patients from the one year follow-up were not reported. Of these 13, three had lumbar spine surgery after the one-year follow-up and one patient died. Nine patients could not be contacted. There was no major device or intraprocedural adverse event during the two-year follow-up. Mean VAS for this 45 patient cohort at 2-year follow-up was 4.8 (95% CI ± 0.8), a statistically significant change from baseline. Mean ODI value at two year follow-up for this cohort was 39.8 (95% CI ± 7.38), a statistically significant from baseline. For 37 patients, ZCQ overall symptom severity score at two-years was 2.7 (95% CI ± 0.2). For 38 patients, ZCQ physical function domain score was 2.6 (95% CI ± 0.4), a statistically significant difference from baseline. They do not report any additional therapies such as pain medications, injections, or physical therapy. The author concluded, “In this report of 2-year follow-up on 45 patients treated with mild percutaneous lumbar decompression, patients experienced statistically significant improvement in pain levels and functional mobility.”
Levy RM and Deer TR. Systematic safety review and meta-analysis of procedural experience using percutaneous access to treat symptomatic lumbar spinal stenosis. Pain Medicine 2012; 13:1554-1561.
The authors stated, “The purpose of this systematic safety review is to report multicenter procedural safety results of patients treated with percutaneous lumbar decompression.” The patient information appeared to come from a variety of sources including retrospective data and publications. The exact methods were not reported. The review included 373 reported patients in 31 centers in the United States and one in Canada from January 2008 to November 2011. The authors reported there were no major device or procedure-related adverse events, but do not give a time frame of follow-up. Major adverse events were defined as any device or procedure related finding that required intervention.
4. MEDCAC
The MEDCAC was not convened for this review.
5. Evidence-based guidelines
No guidelines that referenced evidence were found.
6. Public Comments
Initial 30 day comment period - (04/05/2013 – 05/05/2013)
During the initial 30 day comment period, CMS received 114 comments. A summary of these comments can be found in the proposed decision memorandum and the complete text of these comments is available on the CMS website at View Public Comments (http://www.cms.gov/medicare-coverage-database/details/nca-view-public-comments.aspx?NCAId=269).
Public Comments on Proposed Decision Memorandum
CMS received 201 comments on the proposed decision. Of the 201 comments, 195 advocated for coverage (or coverage with evidence development (CED)) of PILD, five advocated for non-coverage, and one was unclear. One hundred and fifty-eight comments were identified as being from physicians and of these 125 stated they performed the PILD procedure. All physicians identified as being performers of the procedure advocated for coverage. Six comments were identified as being from patients who had the procedure and all advocated for coverage.
There were six comments from eight national physician organizations. Of these comments, the American Society of Anesthesiologists (ASA), the American Academy of Pain Medicine (AAPM), and the American Society of Interventional Pain Physicians (ASIPP) (two comments) advocated for coverage of PILD. The North American Spine Society (NASS) advocated for coverage with evidence development (CED). A combined comment from the American Association of Neurological Surgeons (AANS), the Congress of Neurological Surgeons (CNS), and the AANS/CNS Joint Section on disorders of the Spine and Peripheral Nerves advocated for non-coverage.
There was one comment from America’s Health Insurance Plans who advocated for non-coverage. There were two comments from device manufacturers who advocated for coverage (one for CED). One comment from a group that represents medical technology companies advocated for CED or local Medicare Contractor policy discretion.
Numerous commenters cited references. All references were reviewed for relevance to the scope of the NCA and a list of these references is provided in Appendix B. The references that were determined to be relevant to the scope of the NCA are incorporated into the review and included in the bibliography.
Proposed National Noncoverage
Comments: Many of the commenters opposed the proposed national noncoverage.
Response: We appreciate the input of the commenters. However, we do not have adequate evidence to determine that PILD is reasonable and necessary under 1862(a)(1)(A). We have, for reasons described more fully in the Analysis, determined that PILD will be covered by Medicare only when furnished in a clinical study under section 1862(a)(1)(E) through Coverage with Evidence Development (CED) for beneficiaries with LSS who are enrolled in an approved clinical study that meets specific criteria. While there is limited evidence on the treatment of LSS with PILD, LSS is prevalent in the Medicare population, and we believe that CED studies have potential to answer important questions about this treatment for our beneficiaries.
CED
Comments: Vertiflex, a developer and manufacturer of direct decompression system, requested CED to allow Medicare support for the opportunity to collect robust data on this technology. They stated they have a clinical study under development to evaluate outcomes for their decompression system. They stated, “We recognize evidence is yet insufficient, but further study is warranted given the preliminary experience. Finally, in terms of the effort and expense required to conduct an adequate trial, it is difficult for a small company to organize and fund a robust clinical study comparing newer innovations with more-established procedures for lumbar spinal decompression.”
The recommendation from NASS “…at this time is that CMS refrain from making a final decision regarding the utility of this technology, which is potentially promising in a select group of patients. Our hope is that future studies will be conducted which will provide categorical data that will clarify the proportions and characteristics of patients who are most likely to benefit from the PILD procedure, and the degree to which these patients benefit. Additional studies, independent of industry funding and involvement, are needed. Data at time frames greater than one year, which are clearly lacking, and additional data at up to two years, would be beneficial in determining the overall utility of the procedure. Ideally, predictive factors could be identified to help differentiate which patients are most likely to have a positive or negative response to this procedure.
NASS believes that it is premature to deny the coverage of PILD based on limited research and would like to request CMS to consider including this procedure for further discussion under ‘Coverage for Evidence Development’ category until more data is collected and have sufficient evidence available to determine the utility of this procedure.” However, NASS also stated, “With this new technology, strict indications must be set and observed. Until better comparative data is available, we recommend coverage on a case-by-case basis where indications are met and value may be predicted.”
One commenter suggested that CMS coverage for new medical technologies should be established through local Medicare Contractor policy discretion or through CED.
Response: CMS agrees that management of chronic pain from LSS is a complicated issue with an immature evidence base that is insufficient for broad coverage. More work needs to be done to optimize the ascertainment and reporting of patient centered outcomes. As we discuss further below, the lack of consensus on patient selection criteria is of particular concern and we believe that this can be clarified with further research. Therefore, we agree with these commenters and have decided to support further research on PILD under section 1862(a)(1)(E) of the Social Security Act for beneficiaries with LSS who are enrolled in an approved clinical study. CMS believes that CED will provide the opportunity for the development of high quality evidence for this procedure to answer the important questions of treatment effect, appropriate patient selection criteria and duration of benefit.
The following additional issues were raised in the comments on the proposed noncoverage decision. We address them in detail below, recognizing that the final decision is CED rather than noncoverage and thus the comments may address issues that have been mooted in whole or in part by our final decision.
Patient Selection Criteria
Comments: A number of commenters claimed that patients with LSS have unmet needs and promoted the patient selection criteria that they use in determining if a patient should have the procedure. A commenter stated the most important aspect of any procedure/surgery is patient selection. One commenter suggested that a better description of which patients benefit most and circumstances that would be covered should be defined. A commenter stated that patient selection remains difficult.
The suggested patient selection criteria varied greatly. The suggested criteria ranged from patients with symptomatic central canal stenosis who are not candidates for surgery or who choose not to have laminectomy to more defined criteria that include: 1 –Neurogenic claudication that failed conservative treatment, 2- Inability to walk unsupported for more than 300 feet, 3 – Lower back pain and bilateral leg pains and/or numbness that is relieved by sitting or bending forward, 4 – Imaging evidence that the LF is the main cause of LSS, 5 – No evidence of lateral recess stenosis or radiculopathy, 6 – No evidence of structural spine abnormality or instability like spondylolisthesis.
A comment from the American Society of Anesthesiologists stated that PILD is not appropriate for all patients with LSS and there must be clear guidelines in place to determine patient selection however, they asked CMS to allow opportunity for interested stakeholders to address concerns raised in the decision memo.
However, another commenter stated that the procedure, in general practice, is not performed only on those individuals with lumbar ligamentous hypertrophy contributing to lumbar spinal stenosis, but is often done on individuals with facet arthropathy and disc bulging contributing to the stenosis. Some commenters said that patient selection should be based on if HLF is identified as the main pain generator.
Response: As is evidenced by the comments, there is no consensus on patient selection criteria for PILD. In addition, as demonstrated by the wide variety of examples we received as public comments, including from the physicians performing the PILD procedure, there is no agreed upon standard for identifying the appropriate patient population for the procedure. For example, while hypertrophic ligamentum flavum is the putative target for this therapy; it is not clear how this can be identified as the main pain generator when neural compression is typically caused by hypertrophied bone as well as ligamentum flavum. We agree that patient selection is an important evidence gap, and that quality clinical studies, such as those required under this final NCD, will help close the gap.
Clinical Trial Issues - Confounders including placebo effect
Comments: A number of comments addressed the placebo effect. Some commenters did not believe there was a placebo effect. Some opined that the placebo effect would not last for long periods of time and was not a factor in their patients that experienced relief from pain out to two years. One commenter concluded the placebo effect was not a factor by giving an example of a patient with a diagnosis of Alzheimer’s who appeared to experience relief after the MILD procedure and who didn’t remember having the procedure. Another commenter stated he did not believe his elderly population was susceptible to it on a long term basis. Yet another commenter stated the placebo effect is a significant risk in all of medicine and is not specific for minimally invasive surgical procedures or interventional pain procedures.
Numerous commenters acknowledged concern about the placebo effect, but identified that this was a possibility in all pain procedures, including laminectomy. Another commenter explained he did not solely look at pain scores to judge the outcomes of any procedure; his experience was that functions improved. He stated he would rather have the placebo effect from the MILD procedure versus the rampant narcotic use.
Another commenter expressed his belief that the concerns identified in the NCA about the placebo effect and other methodologic biases in the evidence base did not hold up to the published data and his personal experience. This commenter asserted that there is no study on long term placebo effects that demonstrate significant improvements in outcomes sustained over a year or responder rates that are in the 80% range. In addition, the commenter claimed that since these studies were conducted over 15 sites, an across the board placebo effect becomes very doubtful.
A commenter claiming to be an expert in the area of clinical trial confounding stated that at present there are no placebo-controlled trials for surgical interventions for back pain. He stated that “the data available for PILD suggest significant improvements in both pain and disability ratings which exceed the expected cumulative rate of placebo response, regression to the mean and changes due to natural history expected in persistent low back pain.”
ASIPP pointed out that they are not aware of any peer reviewed published literature on long term placebo effect.
Response: CMS believes that when claims of treatment effect are made, it is important to understand confounders and other factors that would contribute to the apparent impact of a treatment, in order to truly understand if the treatment in question is causing the observed result. These phenomena can include what some call expectation response (placebo effect), fluctuation in symptoms independent of treatment, variability in the natural course of the disorder, regression to the mean in pain intensity, other concurrent treatments, or even response bias in respect to symptom reporting. All of these confounders, including the placebo effect, can limit the persuasiveness of evidence on the treatment of pain. Thus it is critically important to mitigate this limitation by using methodologically robust study designs. A lack of evidence on a long term placebo effect is not the same as evidence of the absence of a long term placebo effect. We cannot reasonably generalize the reported absence of post PILD procedure recollection in a patient with Alzheimer’s Disease to the broader beneficiary population. Therefore, we have finalized this NCD using CED to support good clinical studies to answer these important evidentiary questions.
Durability of Benefit from PILD
Comment: A commenter stated, “Whereas there is uncertainty on the durable benefit of MILD, there is also the confounding variable of progressive degeneration. As compared with more aggressive forms of surgical decompression, the probability of adverse events has been shown to be lower with equivocal beneficial effects.”
A number of commenters disagreed with CMS’ concerns about durability of benefit and pointed out that the studies on MILD and their own case experience shows a continued benefit out to two years and for some greater than two years.
A number of commenters stated that nearly all reported case series reported follow-up data – many as long as one or two years and were puzzled by CMS’ analysis that stated case series for PILD did not report patient follow-up data.
Response: CMS believes that durability of benefit is an important evidentiary question. A beneficiary’s preferences are informed by the ability to consider potential benefits and harms among the available therapeutic options. This consideration is significantly limited if the likely duration of benefit is unclear. The available evidence is of little help; it is difficult to determine duration from case series reporting where confounders such as additional treatments could have important unrecognized effects. The only published RCT was structured for six week follow up for both “as-treated” groups, with the control group not reported as measured at 12 weeks. CMS notes that the largest study in the published literature reflects 373 procedures with limited experience beyond two years. Thus we believe that attention to the reported assessment period is clinically appropriate.
RCTs
Comment: A number of commenters believed that randomized controlled trials with surgery or sham as a comparator are impossible to do. They stated all patients would want the minimally invasive procedure and that sham trials are unethical. One commenter stated that data mining and registries are sufficient to prove effectiveness and safety.
Response: If patients are in fact surgical candidates then surgery would be a reasonable and appropriate comparator. However, there are other minimally invasive procedures that could also be comparators, or the trial could have several arms. If patients are not surgical candidates then a minimally invasive sham procedure as a comparator would be an option. Patients would be receiving other therapies for their pain so they would not be without treatment. While complete, well-done registries can give evidence on safety, they cannot demonstrate causality.
Harms
Comments: Many commenters expressed the opinion that PILD is very safe. They claim that published data supports this contention.
Response: We do not claim that PILD cannot be safely furnished when performed by experienced physicians on appropriately selected patients. However, the lack of physician consensus on patient selection criteria is clearly a fundamental concern. The harms of a procedure may accrue beyond the post-procedure period that is commonly reported in certain studies. For transparency, adverse events and the systematic method of their ascertainment should be clearly defined and reported. All possible adverse events should be reported, even if at first glance they appear to be unrelated to the device or procedure, as the condition could have been exacerbated by the procedure.
General Issues
Comments: There were numerous comments from physicians who perform the procedure who reported anecdotal good outcomes and few to no complications or adverse events for their patients. A number of commenters pointed out that patients who do not improve still have the option of continuing with non-surgical care or opting for open decompression.
Response: CMS appreciates the input of the many physicians sincerely conveying their personal experience with PILD. However, evidence from well-designed methodologically robust clinical studies is more persuasive to draw confident conclusions about the impact of medical technologies. As we state in the General Methodologic Principles in the Appendix to this decision memorandum, anecdotal reports are subject to biases and do not carry the evidentiary weight of methodologically appropriate clinical studies.
Comments: Numerous commenters claimed that MILD is an advancement in pain management, offering relatively safe, minimally invasive, relatively inexpensive, outpatient procedure to a patient population of older, medically complicated patients.
Response: While the conclusiveness of the commenters’ sentiments may ultimately be demonstrated with further research, we cannot share their confidence at this time. Though public comment informs our decisions, we accord greater evidentiary weight to peer reviewed, published, scientific evidence that minimize the impact of bias and confounding.
Comment: One commenter was concerned that the societies that represent interventional pain specialties were not consulted during the NCA process.
Response: The public comment process allows for all interested parties to submit comments on the topic of interest, this includes all specialties that have an interest in the topic. There are many physician professional societies whose members’ expertise is relevant to our review of PILD. We do not believe that an open and transparent process would have been served in this case by narrowing our focus to any single society.
Comments: Some commenters addressed statements in the evidence and analysis to clarify results in their publications.
Response: CMS appreciates this commentary, however the CMS evidence review and analysis is based on what is presented in the published article. We encourage following the CONSORT standards for published articles as this reflects transparency and encourages a critical appraisal of the evidence.
Comments: There was disagreement about the characterization of the case series as weak based on the use of the General Methodological Principles of Study Design (Appendix A). ASIPP suggested that this was inconsistent with AMA’s CPT process which is based on Agency for Health Care Policy and Research (AHCPR1992.) They also claimed that the appraisal conducted in the NCA was not a systematic review, that no methodology was described and; and that a well-accepted Level of Evidence grading scale was not applied.
Response: The CPT process is fundamentally about procedure coding and we do not believe it should determine the evidence review process for NCDs. CMS’ literature search criteria are listed and known trials of PILD were included. No new evidence on PILD in the peer-reviewed published literature was presented in public comment. While CMS believes the evidence does not support coverage under 1862(a)(1)(A), we have concluded that coverage under CED in approved clinical studies will provide the opportunity to answer the evidentiary questions that surround PILD.
Comment: Another commenter supported the proposed decision for non-coverage of PILD, emphasizing that the clinical criteria for establishing the diagnosis of LSS are not standardized and thus could potentially lead to misuse. The comment referenced a 2010 technology assessment on PILD completed by the AANS that determined that no definitive statements could be made concerning indications, efficacy, outcomes, or complications.
Response: CMS appreciates this supportive comment. CMS believes that providing limited coverage in approved clinical studies through CED will provide the opportunity for the development of high quality evidence for this procedure to answer the important questions of treatment effect, appropriate patient selection criteria and duration of benefit.
Comment: Many commenters claimed that CMS covers other treatments without much evidence so we should not hold this therapy to a higher standard. Commenters claimed in that context that the evidence is sufficient to warrant full coverage. Another claimed CMS did not examine the evidence for PILD. However, one group opined that the current literature is of low quality and while the literature suggests the procedure is safe, the improvements in the patients did not meet a minimally acceptable outcome based on definitions.
Response: In making coverage determinations under section 1862(a)(1)(A), the Secretary has discretion to use the NCD process, or other methods, to determine whether an item or service is reasonable and necessary to diagnose or treat an illness or injury or to improve the functioning of a malformed body member. Each NCD must be judged by the medical and scientific evidence that is specific to the particular item or service. With respect to PILD, we have found that the evidence is not sufficient to support coverage under the statutory criteria established in section 1862(a)(1)(A). CMS has specifically noted that the evidence for PILD is limited and bases this conclusion on the available published literature. We further note that no new relevant published studies were identified in the public comments. With that said, while there are gaps in the current evidence base, we believe that there are good clinical studies that may be done to fill in the evidentiary gaps of the current evidence base. Therefore, CMS would like to support methodologically sound studies through coverage with evidence development (CED) NCD.
Comments: Some commenters said they did not understand denying coverage for PILD based on a lack of consensus of diagnostic and treatment criteria for LSS. Others stated that CMS believes that a lack of consensus on diagnosis of LSS means it does not exist. Some also claimed that each patient is different so treatments will vary, which does not support any consensus.
Response: The proposed noncoverage was not based solely on the paucity of evidence of consensus on patient selection. The lack of clearly detailed clinical consensus for diagnosis and treatment of LSS weakens the claim of well-defined patient selection and well-defined care that would consist of standard, evidence driven treatment algorithms. Therefore, it is difficult to be certain of the appropriateness of criteria by which patients were selected or rejected for treatment and what impact various treatment schemes have on these patients both before the procedure as well as concomitant with.
We did not claim that LSS does not exist as an anatomic finding, LSS is known to exist. What are lacking are clear consensus pathophysiologic criteria for the clinical symptoms and reliable guidance on patient management, which leads to idiosyncratic treatment and is not responsive to patient needs. By finalizing this NCD with CED, we believe some of these important questions can be answered.
Comments: Many commenters were of the opinion that other treatments for LSS were either ineffective and/or unsafe and believed that PILD filled the perfect niche in being minimally invasive yet capable of debulking similar to surgery, and therefore should be covered. They stated outcomes for LSS with the SPORT trial were bad so an alternate treatment to open surgery is needed.
Response: The absence of a recognized beneficial treatment is not a reasonable justification for the abandonment of an evidence based paradigm. Rather, we believe that it identifies clinical areas where evidence development is needed to give patients better options. CMS believes that it is important to have evidence based treatment guidelines to help clinicians chose the best therapies for patients to maximize benefit and minimize risk.
Comments: A number of commenters disagreed with the CMS position that there are other available options including minimally invasive techniques for laminectomy. ASIPP claimed that these options do not meet the clinical evidence standard set out in the NCD and ignore the treatment gap that exists between conservative treatments and surgery.
Response: We appreciate the comment. Our evidence review was limited to PILD for LSS.
Comments: Numerous commenters talked about the putative mechanism of action of the PILD procedure. It was offered that the treatment effect is correlated to improvement in epidural flow patterns after debulking of the enlarged ligament, clearly visible fluoroscopically, and correlated with diminished intracanal pressure, improved epidural flow and radically different pressure flow patterns above and below the stenotic level. Another commenter stated the mechanism of action is clear and visible when performing the procedure. It was also stated that a small bit of ligament obstruction of the nerves can have a big clinical effect. Yet another commenter opined that studies on radiologic outcomes are warranted to confirm the long term physiologic and mechanical changes.
While another commenter stated that they believed that the CMS assessment was correct in that there is not sufficient evidence showing adequate or inadequate decompression of the canal. However, they stated the imaging requirement should be irrelevant because the real interest in any study is how the patient is doing clinically. They further stated that requiring cross-sectional imaging following a study is needlessly expensive, particularly if the patient’s symptoms have improved.
Response: We agree that mechanical debulking of the ligamentum flavum is the purported mechanism of action. While with open or endoscopic surgery operators guide their debulking by direct observation, with PILD the debulking is guided by indirect visualization with an epidurogram where flow of contrast is supposed to reflect reduction of nerve compression, though this has not been proven. The debulking with PILD has not been demonstrated with conventional technique such as MRI. It is common for radiographs not to correlate with outcomes in the treatment of back pain, as well as in those who present with pain. Nevertheless, if the procedure is to rely on mechanical debulking it would stand to reason that one could prove mechanical debulking was occurring.
Comments: Many commenters claimed that many elderly patients with LSS who are not candidates for open surgery would be left without any effective treatment options. A common theme throughout the comments was that this therapy fits an important unmet need between conservative treatments and surgery, especially for patients who need decompression but aren’t good surgical candidates or who make a choice not to have open surgery. A commenter stated that after failing conservative treatments, the only option left is PILD or open surgery. Some are too sick to have open surgeries, some are too young and active to have major back surgeries and some are completely against having surgery.
One commenter stated that without the availability of the PILD procedure patients are subjected to choosing possible harmful and fatal surgeries or chronic dependence on opioids. The concern about the high use of opioids and inherent side effects in the elderly population for management of pain was expressed by a number of commenters.
One commenter clarified that MILD does not approach stenosis as a whole, it treats LSS with neurogenic claudication and addresses one-causal factor – the HLF. He stated that this is a condition where you treat the story (the clinical presentation of the patient) and he opined that this has been clearly defined and outlined in the 10 clinical trials.
Another commenter offered that compared to options offered to patients with LSS, this is the most effective and least invasive. A commenter stated that this procedure has the best benefit to risk comparison. A number of commenters talked about the low risk and absence of adverse events associated with this procedure compared to open surgical spine procedures for the treatment of LSS. A number of commenters talked about alternatives, such as medication management which is poorly tolerated in the elderly population, epidural injections with transient success, and open decompression with high risk and difficult recovery or living with pain which is unacceptable and inhumane.
Response: We do not believe that a purported unmet need is justification for unconditional use of inadequately supported care. That would seem to perpetuate rather than solve the problem. Our elderly beneficiaries should not be relegated to a strategy that would consign them to treatment options that will not be rigorously evaluated for meaningful health outcomes. While CMS supports efforts in the development of treatments that are less invasive, we believe it is essential that the evidence support a clearly identified benefit for our Medicare beneficiaries. This type of convincing evidence is established through well-designed, methodologically sound clinical trials. We believe our decision to allow coverage under CED for PILD for LSS will provide the opportunity to develop high quality evidence around this procedure.
Comments: There were a number of comments claiming that CMS had deemed the procedures safe enough to do in an ASC when it determined that CPT code 0275T met the criteria under section 416.166 and would be safely performed in the ASC setting. Some expressed that the conclusions in the NCA were inconsistent with this CMS determination. One commenter asserted that the PILD procedure meets all the statutory requirements for coverage by contractors set out in LCD L28248, is covered by a local Medicare contractor and cited the statutory language from §1862(a)(1)(A) stating that Medicare may not pay for care that is not reasonable and necessary. He went on to state that CMS deemed the procedure safe in the ASC and deemed a reimbursement rate for the PILD procedure in an outpatient setting. He further referenced the Medicare Integrity Manual regarding the LCD Development Process regarding the need for less stringent evidence when allowing for individual consideration.
Response: Coding and payment classifications are not coverage determinations under section 1869(f). Moreover, the ability to submit a claim for furnishing a procedure in any particular setting is not a guarantee that the procedure is clinically beneficial for the patient or that Medicare will pay the claim. Local coverage determinations may not conflict with a national coverage determination and our contractors must follow this NCD when it is effective. 42 CFR 405.1060. As noted above the Secretary has the discretion to determine when the NCD process is applied.
Comments: A number of commenters promoted that this was a lower cost alternative to open surgery. One commenter stated that MILD accomplishes what every new procedure should strive to achieve: “Low cost, high safety ratings, excellent functional (objective) outcomes.”
Response: As a matter of policy, CMS does not consider cost in making NCDs under §1862(a)(1)(A). We also note that other commenters have stated that surgery is not an appropriate comparator to PILD.
Comment: AAPM claimed that the CMS proposed decision was an overly restrictive application of evidence based methodology. They further commented that their goal was to initiate broader-based dialog concerning the CMS approach to coverage decisions for procedures whose evaluation may be better accomplished by effectiveness research rather than the efficacy model relied upon by CMS, as described in Appendix A of the proposed decision memorandum. In addition, they stated that complex conditions, including pain conditions, are common throughout medical practice and it is likely that large numbers of patients will need to be assessed in order to identify which subgroups are likely to respond.
Response: We look forward to the ongoing dialog with the physician community and we believe that CED supports this interest. CMS considers many types of evidence in our NCA process, however some evidence provides more evidentiary weight in informing our decisions. We do consider high quality, well designed observation research seriously; however, there was none for PILD. We do not consider the uncontrolled case series for the PILD procedure to be representative of high quality or reliable evidence on which to base a positive coverage decision under 1862(a)(1)(A). A broad discussion of effectiveness vs efficacy research is not within the scope of this NCA.
Comment: One commenter disagreed that disparities are not addressed in the literature. They added that the literature documents that pain complaints are often taken less seriously, and dealt with less aggressively, in older persons than in younger persons.
Response: While we did not find information about disparities in the PILD literature, we have included some information about disparities in pain management in our final decision memorandum.
Comment: One commenter believed CMS was biased against the pain medicine profession and found the mention of placebo effect as offensive.
Response: We disagree. Pain is an important symptom and chronic pain is clearly a significant burden on beneficiaries. Pain management is often clinically challenging and may expose the patient to procedural or medication risks. We believe that placebo effects are important to exclude in pain management strategies so that patients are not unnecessarily exposed to potential harms. We base our decisions on a review of the peer reviewed scientific evidence and consideration of the placebo effect is part of that review and analysis of the evidence of outcomes of benefit for our Medicare population.
Comment: A commenter expressed that he thought the MILD procedure was dangerous and was being done for other reasons than HLF.
Response: CMS takes note of this comment. However, we believe that the patient protections in bona fide clinical studies afford sufficient confidence for us to apply CED in this case.
Numerous commenters provided references with their comments. All references were reviewed for relevance to the scope of the NCA and a list of these references is provided in Appendix B. The references that were determined to be relevant to the scope of this NCA are incorporated into the bibliography.
The comments can be viewed in their entirety on our website at http://www.cms.gov/medicare-coverage-database/details/nca-view-public-comments.aspx?NCAId=269.
VIII. CMS Analysis
A. Introduction
National coverage determinations (NCDs) are determinations by the Secretary with respect to whether or not a particular item or service is covered nationally by Medicare (§1862 of the Social Security Act).
In order to be covered by Medicare, an item or service must fall within one or more benefit categories contained within Part A or Part B, and must not be otherwise excluded from coverage. Moreover, section 1862(a)(1) of the Social Security Act in part states, with limited exceptions, no payment may be made under part A or part B for any expenses incurred for items or services:
- which are not reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member (§1862(a)(1)(A)).
- In the case of research conducted pursuant to section 1142, which is not reasonable and necessary to carry out the purposes of that section. ((§1862(a)(1)(E)).
Section 1142 of the Social Security Act describes the authority of the Agency for Healthcare Research and Quality (AHRQ). Under section 1142, research may be conducted and supported on the outcomes, effectiveness, and appropriateness of health care services and procedures to identify the manner in which diseases, disorders, and other health conditions can be prevented, diagnosed, treated, and managed clinically.
Section 1862(a)(1)(E) allows Medicare to cover under CED certain items or services for which the evidence is not adequate under section 1862(a)(1)(A), and where additional data gathered in the context of clinical setting would further clarify the impact of these items and services on the health of Medicare beneficiaries. CED, for example, allows CMS to determine that an item or service is only reasonable and necessary when it is provided within a research setting where there are added safety, patient protections, monitoring, and clinical expertise. For the readers’ convenience, the 2006 CED Guidance Document is available at http://www.cms.gov/Medicare/Coverage/DeterminationProcess/downloads/CED.pdf.
As noted earlier, our review sought the answer to the question below. We have repeated it here for the convenience of the reader.
Is the evidence sufficient to conclude that PILD improves health outcomes in Medicare beneficiaries with lumbar spinal stenosis?
There are several fundamental limitations of the evidence that cause us to reach conclusions that disagree with the conclusions of the studies that have been used to support claims of clinical benefit. The absence of diagnostic consensus leads us to question whether the enrolled study subjects indeed have LSS, and if so to what degree. The absence of diagnostic consensus constrains any significant consensus on treatment. The general reliance on incompletely reported case series rather than robust randomized sham controlled clinical trials with explicit protocol driven criteria further limits the persuasiveness of the evidence. These limitations are particularly challenging with back pain in light of subjective nature of patients’ symptoms and the failure to adequately account for the biases and confounding that include placebo effects and spontaneous symptom improvement in the natural history of the condition. We describe these concerns in greater detail below.
Lack of consensus on diagnostic criteria
Based on our review, we are concerned that the lack of consensus on the definition of spinal stenosis poses a significant challenge to the persuasiveness of the available evidence that might be used to support PILD coverage. Given the conditions and anatomic variations that lead to complaints consistent with LSS, the application of explicit and reproducible diagnostic criteria are needed to assure that patients in clinical trials are comparable to patients in community settings who may be labeled with the same diagnosis.
Unfortunately, the available clinical studies generally did not include consistent explicit descriptions of their diagnostic criteria when they reported other descriptive information. This makes it difficult for the reader to understand whether the reported results are generalizable to individual patients (i.e., do these enrolled subjects have the same characteristics as my patient) or to the broad Medicare beneficiary population. This lack of consensus has been cited by others.
- Presumed diagnosis can be postulated with clinical symptoms and radiographic studies, but, “There is no criterion standard for the clinical diagnosis.” (Haig 2006)
- For radiographic studies, “No consensus exists regarding the definition of spinal stenosis in terms of the diameter of the spinal canal or area measurements.” (Issack et al 2012)
- Complicating the exact cause and effect, the relationship between objective measurements and subjective symptoms and the degree of narrowing of the spinal canal is unclear. In fact, many patients with radiographic changes consistent with stenosis do not have symptoms. Thus, the “gold standard” for diagnosis as well as treatment of stenosis does not exist. (Sandella et al. 2013)
Other diagnoses can mimic LSS. (Siebert et al. 2009) A number of structural issues, mostly degenerative, can lead to lumbar spinal stenosis. Based on the totality of the evidence reviewed a few common attributes are agreed upon. When we think of LSS we think of some type of connective tissue structural impingement. Accepted qualitative criteria for the diagnosis of lumbar spinal stenosis are the presence of disk protrusion, lack of perineural intraforaminal fat, presence of hypertrophic facet joint degeneration, absence of fluid around the cauda equina, and hypertrophy of the ligamentum flavum. (Mamisch et al. 2012)
Lack of consensus on the treatment of LSS
Non-surgical or conservative care of LSS may include the following either separately or in various combinations: patient education, physical therapy, epidural injections, manual therapy, behavioral therapy, acupuncture, lumbar corset, and pharmacologic intervention. For patients with more severe symptoms surgery is an option. In addition to open techniques, there are minimally invasive techniques for laminectomy.
Because there is no consensus on diagnostic definition for LSS, there is a corresponding lack of consensus on treatment. “Given the considerable pathological and clinical heterogeneity of LSS, the lack of therapeutic recommendations and the large number of distinct therapies, the selection of an appropriate procedure is difficult.” (Siebert et al. 2009) “Class I evidence-based recommendations cannot be made for any conservative or surgical therapy in relation to mid-term and long-term patient outcomes.” (Siebert et al. 2009) In LSS patients without objective neurologic findings such as cauda equina syndrome, it is important to understand which patients will benefit from true structural decompression.
PILD as a treatment
The recognition of a plausible mechanism of action is necessary if a treatment is to be deemed efficacious. Uncertainty leads to reasonable doubt that a witnessed event is causally related to any specific intervention. For invasive treatments there is generally a well-defined structural target. One does not operate on pain per se, but on the pain generator.
The stated goal of PILD is to reduce the thickness of the ligamentum flavum and thereby reduce the connective tissue impingement that is believed to cause the pain. The procedure relies upon removing various types and amounts of connective tissue to conform to a radiographic picture of intraoperative fluoroscopy (with epidural contrast) to reduce the functional stenosis. One article describes this as removing 20 to 50 fragments of bone and ligamentous tissue per single hemilaminar segment, with each fragment measuring between 0.5 to 3 mm in maximal dimension. We cannot be certain that removing a few tiny segments of connective tissue with the PILD tool makes any real structural difference despite the fluoroscopy image of the patient bent forward during the procedure. As with any invasive procedure where tissue is altered, changes from the preoperative radiographic evaluation should correlate with outcomes after decompression, as it is a mechanical debulking that is attempted for neural decompression. (Mattei 2013) The only post-procedure study to date, which is small, suggests this does not happen. (Wilkinson and Fourney 2012)
Analysis of evidence for PILD as a treatment
Case Series
Case series design is commonly used in reports of therapies. Carey and Boden (2003) in Spine suggest that case series can provide some important information in the area of case definition, trend analyses regarding outcomes, and hints as to causation; however, high quality case series study design and reporting is required to be able to obtain useful information for patient management. While there are conveniences in reviewing case series their methodologic limitations reduce their evidentiary persuasiveness. Case series cannot adequately control for bias and confounding and thus do not provide conclusive evidence in the true benefit or harm of an intervention. This is particularly troublesome for interventions addressing pain, such as the PILD procedure, where the placebo effect introduces a significant risk of bias.
We cannot determine from the published reports what prior therapies were attempted without success. The PILD reports do not furnish enough detail about their protocols to allow other investigators to replicate the studies. For example, does the fluoroscopic endpoint which is reported as procedural success vary depending on how the patient is positioned or on other variables, or is it somehow standardized? Does the contrast media contain anesthetic or steroid? What co-interventions were used, as patients generally receive multiple co-interventions?
The case series for PILD did not report easily interpretable patient follow-up data where we are confident of durable treatment effect due solely to the PILD procedure. Thus we cannot determine whether even any transient effect is present for long enough to signify durable benefit or harm. Less evidentiary weight is given to studies that do not report information that is important in understanding the ultimate impact of the intervention on the patient.
The PILD case series lacked reporting of co-interventions. Typically, patients with LSS receive a variety of co-interventions. If additional treatments are furnished, such as analgesic medications or physical therapy, and there is no controlling for these confounders, it is difficult if not impossible to ascertain PILD treatment success or failure. Without reporting relevant co-interventions results may not be replicated. It could give the appearance that the reported treatment is causal to a successful result, when in fact it is the unreported active treatment, such as narcotic analgesics, that is the causal factor.
The PILD case series did not define key patient indications well. Therefore, we do not know who, if anyone, will benefit from the procedure. In some of the PILD studies, the inclusion criteria require a ligamentum flavum of > 2.5mm, others > 4.0 mm, and still other studies the thickness is not mentioned. In the Lindren and Grider study the authors stated, “The lack of documented ligamentum flavum thickening for each patient is a drawback to the current study. Future studies could attempt to standardize the selection criteria of patients for this procedure with vigorous determination of ligamentum flavum thickness perhaps better predicting who will benefit from the procedure.” The important point may be that ligamentum flavum thickness, despite being the treatment target, does not appear to matter to the reported results.
Many of the PILD studies had short or variable follow-up. While some patients over their followed time appeared to have reduction in pain, pain did not appear to be alleviated completely as witnessed by VAS scores > 0. We do not know if this pain worsened or in the case of those that were pain free at the time of measurement recurred, necessitating narcotics or surgery. Many of the studies had significant missing data. It is important to understand why data was missing, as it could be that these patients had worsening problems and sought care elsewhere. There were no clear definitions of success or failure. This matters when we try to interpret outcome data. For instance, Chopko 2011 reported a statistically significant VAS change, but no change in ODI, this does not support a positive VAS outcome. Clinically significant change on an individual basis is meaningful, group means comparison is not. Data can be imputed when it is missing. While last observation carried forward is a popular method, a sensitivity analysis should be done with best and worst case scenarios to give a more complete picture which is lacking in the studies we reviewed. As there is some suggestion that the subjective measures of pain and disability do not correlate well with actual activity level in patients with LSS, it seems beneficial to include other outcome measures of activity and ambulation.
PILD RCT
There was a single randomized trial (Brown 2012) reported. Like the PILD case series we had many concerns with the trial. The trial had a short-term outcome of six weeks, with only the experimental group reported at 12 weeks. It was designed to have 20 subjects per group but ended up having 21 in the experimental group and 17 in the control group without explanation as to why it was different than the trial design. The trial did not clearly define for the reader what definition of conservative care was used. For example, some patients were reported to have a month or less of medical management. Similar to the case series described above, the clinical trial report lacked details of co-interventions. Again, without reporting relevant co-interventions results may not be replicated. It could give the appearance that the reported treatment is causal to a successful result, when in fact it is the unreported active treatment, such as narcotic analgesics, that is the causal factor.
Importantly, the comparator does not appear to be adequate to lead to a conclusion of superiority to an inferior treatment. Patients in the mild group underwent procedures bilaterally and at different levels, whereas patients in the ESI group had only one injection, even though “…there is no consensus among interventional pain management specialists regarding type, dosage, frequency, approach, and total number of injections in ESI therapy, generally multiple injections are administered at various intervals.” (Brown et al. 2012) Blinding was not confirmed. Well-designed and reported RCTs carry the most weight. However, despite the author’s reported positive results the weaknesses in the study design and the lack of reporting on important elements calls into question the value of the study and the confidence of the results.
Some authors such as Schomer et al. have claimed comparable results to other therapies, particularly decompressive laminectomy, touting a better safety profile. Without a head to head trial or at the minimum adequate demonstration of comparable patients this claim is not valid. An alternative to open decompression is minimally invasive decompression that is done under direct observation and has not generally been mentioned in the PILD studies. This technique may be a more appropriate comparison for PILD. Regardless, it is not clear where these therapies fit within the LSS treatment scheme.
Several articles reported a good safety profile, however there have also been serious adverse events reported. Chopko (2011) reported two very serious post-op complications. While it could be claimed that they were not related to the site of treatment, complications nevertheless occurred in these high-risk patients. Tumialan reported on 10 patients with persistent symptoms after the mild procedure, including eight with refractory neurogenic claudication, two patients with cerebrospinal fluid leak, and one with a dural tear and transected nerve roots identified during revision surgery. (Tumialan et al. 2012) He added that all of these patients required additional surgery with exploration. While this is not reported in a peer-reviewed article, it seems unlikely that a physician would falsely call attention to adverse events related to procedures he performed. Although Levy and Deer reported on 373 patients, the data sources were unclear and we cannot be assured of consistent and reliable reporting when data collection methods are not reported in detail. We cannot exclude the duplication of subjects as well as lack of systematic adverse event collection, including failure to report serious complications arising post-op such as the ones in Chopko 2011. It is unclear why only a few studies reported adverse events of significance, or whether the procedure is in fact very safe as some maintain. With any invasive procedure, particularly in the complex area of the spinal cord with direct CSF and nerve connection to the brain, risk is not insignificant and should be realistically accessed and communicated to the patient. Systematic, well-defined methods of data collection and reporting are necessary to provide for rigorous review.
Much of the mild evidence appears to have authorship or other relationships to the manufacturer. A number of the authors of these studies have had a financial relationship with Vertos Medical and the manufacturer provided funding for some of the studies. It is important that well-designed, high-quality clinical trials must address both the complexities and biases, real and/or perceived, that exist. This includes the potential biases from funding sources. Shah’s retrospective review of articles published in the journal Spine identified, “industry supported studies had a greater frequency of positive results than studies with any other funding sources.” (Shah, Albert et al. 2005)
Conflict of interest can be defined as, “A conflict of interest is a set of circumstances that creates a risk that professional judgment or actions regarding a primary interest will be unduly influenced by a secondary interest.” (IOM 2009) Disclosure is a necessary, but not sufficient, element to assess this risk. (IOM 2009) Unfortunately, policies for publications are not uniform, and are sometimes insufficient to deal with the complex nature of relationships.
CMS believes that chronic management of LSS is a complicated issue with an unsatisfactory evidence base. More work needs to be done to optimize patient outcomes, specifically what treatment works for whom and when. We encourage clinical studies that improve the evidence base to inform providers in the provision of optimal patient centered care. It remains to be determined in which patients and also if minimally invasive decompression can be satisfactorily accomplished, but if it can, it could improve patient outcomes. We believe that CED will provide the opportunity to obtain Medicare support to develop a high quality evidence base around this procedure. Therefore, we have determined that PILD will be covered by Medicare when provided in a clinical study under section 1862(a)(1)(E) through CED for beneficiaries with LSS who are enrolled in an approved clinical study that meets specific criteria CMS believes that CED will provide the opportunity for the development of high quality evidence for this procedure to answer the important questions of treatment effect, appropriate patient selection criteria and duration of benefit.
We believe PILD for LSS is an appropriate application of CED. CMS has a particular interest in improved beneficiary function and quality of life, specific characteristics that identify patients who may benefit from the procedure, and the duration of benefit. A clinical study seeking Medicare payment for PILD for LSS must address one or more aspects of the following questions in a prospective, randomized, controlled design using current validated and reliable measurement instruments and clinically appropriate comparator treatments, including appropriate medical or surgical interventions or a sham controlled arm, for patients randomized to the non-PILD group.
The study protocol must specify a statistical analysis that evaluates the effect of beneficiary characteristics on patient health outcomes as well as the duration of benefit.
Specifically, we believe that CED is needed to identify under what conditions, if any, the following questions might be answered affirmatively:
- Does PILD provide a clinically meaningful improvement of function and/or quality of life in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD provide clinically meaningful reduction in pain in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD affect the overall clinical management of LSS and decision making, including use of other medical treatments or services, compared to other treatments?
We expect that an approved clinical study that evaluates the health outcomes of the use of PILD for LSS under CED would have at least the following characteristics:
The trial exhibits a randomized controlled design with an appropriate comparator or sham with justification for the choice of comparator.
The outcomes are pre-specified in the protocol and speak to clinically meaningful improvements, both disease specific and general function measures, for beneficiaries.
The method of the PILD procedure is standardized and designed to assess durable benefit.
There is a detailed protocol driven description and confirmation of the PILD procedure, including level(s) of intervention, side, thickness of LF, amount of tissue removed.
Any treatments in addition to study procedures must be reported. While it is advisable that both the active and comparator groups receive the same appropriate usual care, it is understood that pain treatment is individualized. However, differences in treatment that can confound the results must be appropriately analyzed.
Missing data are accounted for in a methodologically appropriate manner.
Outcomes related to other medical services and treatments for LSS are tracked (e.g. reduction or elimination of opioids/NSAIDs, clinically supervised therapies, interventional procedures, etc.)
The exclusion criteria are appropriate and not unjustifiably restrictive.
The sample size is adequate to detect an appropriate effect size based on pre-specified meaningful outcomes.
The enrolled subjects are representative of the relevant Medicare population. This means that the sample would, at minimum, reflect Medicare-relevant age, gender and racial distributions.
The principal investigator must submit the complete study protocol, identify the relevant CMS research question(s) that will be addressed and cite the location of the detailed analysis plan for those questions in the protocol, plus provide a statement addressing how the study satisfies each of the standards of scientific integrity (a. through m. listed in Section I of this decision memorandum and the NCD), as well as the investigator’s contact information, to the address below. The information will be reviewed, and approved studies will be identified on the CMS website.
Director, Coverage and Analysis Group
Re: PILD CED
Centers for Medicare & Medicaid Services (CMS)
7500 Security Blvd., Mail Stop S3-02-01
Baltimore, MD 21244-1850
B. Disparities
The current PILD literature does not address disparities, with the exception that gender is reported in some studies. However, there is significant information in the literature regarding disparities in pain management. The results of a double-blinded RCT looking at physician management decisions for patients with chronic low back pain and lower extremity pain published in 2009 showed “physician specialty, gender, ethnicity, and professional status significantly affected treatment plans, including analgesic prescription and referrals for invasive therapy.” This study suggested that pain management decisions are influenced by physicians’ demographic variables and perhaps patients’ demographic variables. (Nampiaparampil et al. 2009)
Mills identified that older adults presenting to the emergency department for abdominal or back pain were less likely to receive analgesia and wait longer for pain medication compared to younger adults. (Mills et al. 2011) Racial and ethnic disparities in treatment of pain have been found in all settings and all for types of pain. Green concluded, “There is a need for improved training for health care providers and educational interventions for patients.” (Green et al. 2003)
Summary
CMS identified a number of studies related to the PILD procedure for LSS. The majority of studies were case series which have inherent limitations in providing a level of reliable evidence of benefit for a procedure, especially a procedure addressing pain. The case series for the PILD procedure suffered from additional limitations in failing to report information important for anyone to assess the clinical utility of this procedure for a particular patient. The one RCT had a small enrollment and major design flaws that called into question the results of the trial.
In reviewing the evidence on PILD we are confronted with weak studies, questions about missing information, questions about adverse events and conflicts of interest. After thoroughly reviewing the evidence for PILD for LSS, we have determined the evidence does not support a conclusion of improved health outcomes for our Medicare beneficiaries. However, we recognize that LSS is a real and important source of pain and functional limitation for patients, and that the development of effective minimally invasive procedures could have a potential place in the treatment armamentarium, but that more evidence is clearly needed. In order to support additional research on the development of effective minimally invasive procedures for the treatment of LSS, we will cover this procedure under section 1862(a)(1)(E) of the Social Security Act.
IX. Conclusion
A. The CMS has determined that PILD for LSS is not reasonable and necessary under section 1862(a)(1)(A) of the Social Security Act.
B. The CMS has determined that PILD will be covered by Medicare when provided in a clinical study under section 1862(a)(1)(E) through CED for beneficiaries with LSS who are enrolled in an approved clinical study that meets the criteria below.
CMS has a particular interest in improved beneficiary function and quality of life, specific characteristics that identify patients who may benefit from the procedure, and the duration of benefit. A clinical study seeking Medicare payment for PILD for LSS must address one or more aspects of the following questions in a prospective, randomized, controlled design using current validated and reliable measurement instruments and clinically appropriate comparator treatments, including appropriate medical or surgical interventions or a sham controlled arm, for patients randomized to the non-PILD group.
The study protocol must specify a statistical analysis and a minimum length of patient follow up time that evaluates the effect of beneficiary characteristics on patient health outcomes as well as the duration of benefit.
- Does PILD provide a clinically meaningful improvement of function and/or quality of life in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD provide clinically meaningful reduction in pain in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD affect the overall clinical management of LSS and decision making, including use of other medical treatments or services, compared to other treatments?
These studies must be designed so that the contribution of treatments in addition to the procedure under study are either controlled for or analyzed in such a way as to determine their impact.
- The principal purpose of the research study is to test whether a particular intervention potentially improves the participants’ health outcomes.
- The research study is well supported by available scientific and medical information or it is intended to clarify or establish the health outcomes of interventions already in common clinical use.
- The research study does not unjustifiably duplicate existing studies.
- The research study design is appropriate to answer the research question being asked in the study.
- The research study is sponsored by an organization or individual capable of executing the proposed study successfully.
- The research study is in compliance with all applicable Federal regulations concerning the protection of human subjects found at 45 CFR Part 46. If a study is regulated by the Food and Drug Administration (FDA), it must be in compliance with 21 CFR parts 50 and 56.
- All aspects of the research study are conducted according to appropriate standards of scientific integrity (see http://www.icmje.org).
- The research study has a written protocol that clearly addresses, or incorporates by reference, the standards listed here as Medicare requirements for CED coverage.
- The clinical research study is not designed to exclusively test toxicity or disease pathophysiology in healthy individuals. Trials of all medical technologies measuring therapeutic outcomes as one of the objectives meet this standard only if the disease or condition being studied is life threatening as defined in 21 CFR § 312.81(a) and the patient has no other viable treatment options.
- The clinical research study is registered on the ClinicalTrials.gov website by the principal sponsor/investigator prior to the enrollment of the first study subject.
- The research study protocol specifies the method and timing of public release of all prespecified outcomes to be measured including release of outcomes if outcomes are negative or study is terminated early. The results must be made public within 24 months of the end of data collection. If a report is planned to be published in a peer reviewed journal, then that initial release may be an abstract that meets the requirements of the International Committee of Medical Journal Editors (http://www.icmje.org).
- The research study protocol must explicitly discuss subpopulations affected by the treatment under investigation, particularly traditionally underrepresented groups in clinical studies, how the inclusion and exclusion criteria effect enrollment of these populations, and a plan for the retention and reporting of said populations on the trial. If the inclusion and exclusion criteria are expected to have a negative effect on the recruitment or retention of underrepresented populations, the protocol must discuss why these criteria are necessary.
- The research study protocol explicitly discusses how the results are or are not expected to be generalizable to the Medicare population to infer whether Medicare patients may benefit from the intervention. Separate discussions in the protocol may be necessary for populations eligible for Medicare due to age, disability or Medicaid eligibility.
Consistent with section 1142 of the Social Security Act, AHRQ supports clinical research studies that CMS determines meet the above-listed standards and address the above-listed research questions.
Appendix A
General Methodological Principles of Study DesignWhen making national coverage determinations, CMS evaluates relevant clinical evidence to determine whether or not the evidence is of sufficient quality to support a finding that an item or service falling within a benefit category is reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member. The critical appraisal of the evidence enables us to determine whether: 1) the specific assessment questions can be answered conclusively; and 2) the intervention will improve health outcomes for patients. An improved health outcome is one of several considerations in determining whether an item or service is reasonable and necessary.
CMS divides the assessment of clinical evidence into three stages: 1) the quality of the individual studies; 2) the relevance of findings from individual studies to the Medicare population; and 3) overarching conclusions that can be drawn from the body of the evidence on the direction and magnitude of the intervention’s risks and benefits.
The issues presented here represent a broad discussion of the issues we consider when reviewing clinical evidence. However, it should be noted that each coverage determination has unique methodological aspects.
1. Assessing Individual Studies
Methodologists have developed criteria to determine weaknesses and strengths of clinical research. Strength of evidence generally refers to: 1) the scientific validity underlying study findings regarding causal relationships between health care interventions and health outcomes; and 2) the reduction of bias. In general, some of the methodological attributes associated with stronger evidence include those listed below:
- Use of randomization (allocation of patients to either intervention or control group) in order to minimize bias.
- Use of contemporaneous control groups (rather than historical controls) in order to ensure comparability between the intervention and control groups.
- Prospective (rather than retrospective) studies to ensure a more thorough and systematical assessment of factors related to outcomes.
- Larger sample sizes in studies to help ensure adequate numbers of patients are enrolled to demonstrate both statistically significant as well as clinically significant outcomes that can be extrapolated to the Medicare population. Sample size should be large enough to make chance an unlikely explanation for what was found.
- Masking (blinding) to ensure patients and investigators do not know to which group patients were assigned (intervention or control). This is important especially in subjective outcomes, such as pain or quality of life, where enthusiasm and psychological factors may lead to an improved perceived outcome by either the patient or assessor.
Regardless of whether the design of a study is a randomized controlled trial, a non-randomized controlled trial, a cohort study or a case-control study, the primary criterion for methodological strength or quality is the extent to which differences between intervention and control groups can be attributed to the intervention studied. This is known as internal validity. Various types of bias can undermine internal validity. These include:
- Different characteristics between patients participating and those theoretically eligible for study but not participating (selection bias)
- Co-interventions or provision of care apart from the intervention under evaluation (confounding)
- Differential assessment of outcome (detection bias)
- Occurrence and reporting of patients who do not complete the study (attrition bias)
In principle, rankings of research design have been based on the ability of each study design category to minimize these biases. A randomized controlled trial minimizes systematic bias (in theory) by selecting a sample of participants from a particular population and allocating them randomly to the intervention and control groups. Thus, randomized controlled studies have been typically assigned the greatest strength, followed by non-randomized clinical trials and controlled observational studies. The following is a representative list of study designs (some of which have alternative names) ranked from most to least methodologically rigorous in their potential ability to minimize systematic bias:
- Randomized controlled trials
- Non-randomized controlled trials
- Prospective cohort studies
- Retrospective case control studies
- Cross-sectional studies
- Surveillance studies (e.g., using registries or surveys)
- Consecutive case series
- Single case reports
When there are merely associations but not causal relationships between a study’s variables and outcomes, it is important not to draw causal inferences. Confounding refers to independent variables that systematically vary with the causal variable. This distorts measurement of the outcome of interest because its effect size is mixed with the effects of other extraneous factors. For observational, and in some cases randomized controlled trials, the method in which confounding factors are handled (either through stratification or appropriate statistical modeling) are of particular concern. For example, in order to interpret and generalize conclusions to our population of Medicare patients, it may be necessary for studies to match or stratify their intervention and control groups by patient age or co-morbidities.
Methodological strength is, therefore, a multidimensional concept that relates to the design, implementation and analysis of a clinical study. In addition, thorough documentation of the conduct of the research, particularly study’s selection criteria, rate of attrition and process for data collection, is essential for CMS to adequately assess the evidence.
2. Generalizability of Clinical Evidence to the Medicare Population
The applicability of the results of a study to other populations, settings, treatment regimens, and outcomes assessed is known as external validity. Even well-designed and well-conducted trials may not supply the evidence needed if the results of a study are not applicable to the Medicare population. Evidence that provides accurate information about a population or setting not well represented in the Medicare program would be considered but would suffer from limited generalizability.
The extent to which the results of a trial are applicable to other circumstances is often a matter of judgment that depends on specific study characteristics, primarily the patient population studied (age, sex, severity of disease, and presence of co-morbidities) and the care setting (primary to tertiary level of care, as well as the experience and specialization of the care provider). Additional relevant variables are treatment regimens (dosage, timing, and route of administration), co-interventions or concomitant therapies, and type of outcome and length of follow-up.
The level of care and the experience of the providers in the study are other crucial elements in assessing a study’s external validity. Trial participants in an academic medical center may receive more or different attention than is typically available in non-tertiary settings. For example, an investigator’s lengthy and detailed explanations of the potential benefits of the intervention and/or the use of new equipment provided to the academic center by the study sponsor may raise doubts about the applicability of study findings to community practice.
Given the evidence available in the research literature, some degree of generalization about an intervention’s potential benefits and harms is invariably required in making coverage decisions for the Medicare population. Conditions that assist us in making reasonable generalizations are biologic plausibility, similarities between the populations studied and Medicare patients (age, sex, ethnicity and clinical presentation), and similarities of the intervention studied to those that would be routinely available in community practice.
A study’s selected outcomes are an important consideration in generalizing available clinical evidence to Medicare coverage determinations because one of the goals of our determination process is to assess health outcomes. We are interested in the results of changed patient management not just altered management. These outcomes include resultant risks and benefits such as increased or decreased morbidity and mortality. In order to make this determination, it is often necessary to evaluate whether the strength of the evidence is adequate to draw conclusions about the direction and magnitude of each individual outcome relevant to the intervention under study. In addition, it is important that an intervention’s benefits are clinically significant and durable, rather than marginal or short-lived.
If key health outcomes have not been studied or the direction of clinical effect is inconclusive, we may also evaluate the strength and adequacy of indirect evidence linking intermediate or surrogate outcomes to our outcomes of interest.
3. Assessing the Relative Magnitude of Risks and Benefits
Generally, an intervention is not reasonable and necessary if its risks outweigh its benefits. Health outcomes are one of several considerations in determining whether an item or service is reasonable and necessary. For most determinations, CMS evaluates whether reported benefits translate into improved health outcomes. CMS places greater emphasis on health outcomes actually experienced by patients, such as quality of life, functional status, duration of disability, morbidity and mortality, and less emphasis on outcomes that patients do not directly experience, such as intermediate outcomes, surrogate outcomes, and laboratory or radiographic responses. The direction, magnitude, and consistency of the risks and benefits across studies are also important considerations. Based on the analysis of the strength of the evidence, CMS assesses the relative magnitude of an intervention or technology’s benefits and risk of harm to Medicare beneficiaries.
Appendix B
References submitted through public comments.
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(1) Levy et al (2012) Systemic Safety Review and Meta Analysis od Procedural Experience using Percutaneous Access to treat Symptomatic Lumbar Spinal Stenosis Pain Medicine 13 (12) pages 1554-1561 (2) Mekhail, Nagy, et al (2012) Long term results of Percutaneous Lumbar Decompressio for Spinal Stenosis Journal Pain Practice 12 3 pages 184-193 (3)Deyo et al (2010) Major Medical Complications and Changes Associated with Surgery for Lumbar Spinal Stenosis in Older Adults: JAMA 303: pages 1259-1265 I appreciate your review of this matter."
Chopko, B., (2013), Long-term results of percutaneous lumbar decompression for LSS: Two-year outcomes. Clinical Journal of Pain. doi: 10.1097/AJP.0b013e31827fb803 [Epub ahead of print]. Tumialan L. Regarding: Long-Term Results of Percutaneous Lumbar Decompression MILD for Spinal Stenosis. Pain Practice 2012; Volume 12, Issue 3: 252–253. Benyamin R. Regarding: Dr. Tumialan et al. In Response to Long-Term Results of Percutaneous
Lumbar Decompression MILD for Spinal Stenosis. Levy, R., et al. (2012), Systematic safety review and meta-analysis of procedural experience using percutaneous access to treat symptomatic lumbar spinal stenosis. Pain Medicine. 13(12), 1554-1561. doi: 10.1111/j.1526-4637.2012.01504.x
1Levy, Robert, et al. (2012), Systematic Safety Review and Meta-Analysis of Procedural Experience Using Percutaneous Access to Treat Symptomatic Lumbar Spinal Stenosis. Pain Medicine, 13(12): 1554-1561. doi: 10.1111/j.1526-4637.2012.01504.x
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1. Deyo R., Complex Operations for Spinal Stenosis Increasing Despite Complications, Journal of American Medicine 2010; 303:1259-1265.
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Appendix C
We are including the preliminary language for the national coverage determination which will be effective immediately. The language is subject to formal revisions and formatting changes prior to the release of the final NCD publication in the National Coverage Determination Manual.
Medicare National Coverage Determinations Manual
Chapter 1, Part 2 (Sections 90 – 160.25)
Coverage Determinations
Table of Contents
(Rev.)
150.13 Percutaneous image-guided lumbar decompression for lumbar spinal stenosis
150.13 – Percutaneous Image-guided Lumbar Decompression (PILD) for Lumbar Spinal Stenosis (LSS) (Effective XX XX, 2014)
A. General
PILD is a posterior decompression of the lumbar spine performed under indirect image guidance without any direct visualization of the surgical area. This is a procedure proposed as a treatment for symptomatic LSS unresponsive to conservative therapy. This procedure is generally described as a non-invasive procedure using specially designed instruments to percutaneously remove a portion of the lamina and debulk the ligamentum flavum. The procedure is performed under x-ray guidance (e.g., fluoroscopic, CT) with the assistance of contrast media to identify and monitor the compressed area via epidurogram.
B. Nationally Covered Indications
Effective for services performed on or after XX XX, 2014, the Centers for Medicare & Medicaid Services (CMS) has determined that PILD will
be covered by Medicare when provided in a clinical study under section 1862(a)(1)(E) through Coverage with Evidence Development (CED) for beneficiaries with LSS who are enrolled in an approved clinical study that meets the criteria below.
CMS has a particular interest in improved beneficiary function and quality of life, specific characteristics that identify patients who may benefit from the procedure, and the duration of benefit. A clinical study seeking Medicare payment for PILD for LSS must address one or more aspects of the following questions in a prospective, randomized, controlled design using current validated and reliable measurement instruments and clinically appropriate comparator treatments, including appropriate medical or surgical interventions or a sham controlled arm, for patients randomized to the non-PILD group.
The study protocol must specify a statistical analysis and a minimum length of patient follow up time that evaluates the effect of beneficiary characteristics on patient health outcomes as well as the duration of benefit.
- Does PILD provide a clinically meaningful improvement of function and/or quality of life in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD provide clinically meaningful reduction in pain in Medicare beneficiaries with LSS compared to other treatments?
- Does PILD affect the overall clinical management of LSS and decision making, including use of other medical treatments or services, compared to other treatments?
These studies must be designed so that the contribution of treatments in addition to the procedure under study are either controlled for or analyzed in such a way as to determine their impact.
- The principal purpose of the research study is to test whether a particular intervention potentially improves the participants’ health outcomes.
- The research study is well supported by available scientific and medical information or it is intended to clarify or establish the health outcomes of interventions already in common clinical use.
- The research study does not unjustifiably duplicate existing studies.
- The research study design is appropriate to answer the research question being asked in the study.
- The research study is sponsored by an organization or individual capable of executing the proposed study successfully.
- The research study is in compliance with all applicable Federal regulations concerning the protection of human subjects found at 45 CFR Part 46. If a study is regulated by the Food and Drug Administration (FDA), it must be in compliance with 21 CFR parts 50 and 56.
- All aspects of the research study are conducted according to appropriate standards of scientific integrity (see http://www.icmje.org).
- The research study has a written protocol that clearly addresses, or incorporates by reference, the standards listed here as Medicare requirements for CED coverage.
- The clinical research study is not designed to exclusively test toxicity or disease pathophysiology in healthy individuals. Trials of all medical technologies measuring therapeutic outcomes as one of the objectives meet this standard only if the disease or condition being studied is life
- threatening as defined in 21 CFR § 312.81(a) and the patient has no other viable treatment options.
- The clinical research study is registered on the ClinicalTrials.gov website by the principal sponsor/investigator prior to the enrollment of the first study subject.
- The research study protocol specifies the method and timing of public release of all prespecified outcomes to be measured including release of outcomes if outcomes are negative or study is terminated early. The results must be made public within 24 months of the end of data collection. If a report is planned to be published in a peer reviewed journal, then that initial release may be an abstract that meets the requirements of the International Committee of Medical Journal Editors (http://www.icmje.org).
- The research study protocol must explicitly discuss subpopulations affected by the treatment under investigation, particularly traditionally underrepresented groups in clinical studies, how the inclusion and exclusion criteria effect enrollment of these populations, and a plan for the retention and reporting of said populations on the trial. If the inclusion and exclusion criteria are expected to have a negative effect on the recruitment or retention of underrepresented populations, the protocol must discuss why these criteria are necessary.
- The research study protocol explicitly discusses how the results are or are not expected to be generalizable to the Medicare population to infer whether Medicare patients may benefit from the intervention. Separate discussions in the protocol may be necessary for populations eligible for Medicare due to age, disability or Medicaid eligibility.
Consistent with section 1142 of the Social Security Act, the Agency for Healthcare Research and Quality (AHRQ) supports clinical research studies that CMS determines meet the above-listed standards and address the above-listed research questions.
C. Nationally Non-Covered Indications
Effective for services performed on or after XX XX, 2014, CMS has determined that PILD for LSS is not reasonable and necessary under section 1862(a)(1)(A) of the Social Security Act.
D. Other
Endoscopically assisted laminotomy/laminectomy, which requires open and direct visualization, as well as other open lumbar decompression procedures for LSS are not within the scope of this NCA.
(This NCD last reviewed XX )
(This NCD last reviewed XX 2008)
