Percutaneous Image-guided Lumbar Decompression for Lumbar Spinal Stenosis

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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.

Decision Memo: 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 ≤ 100mm 2 , 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