Continuous Positive Airway Pressure (CPAP) Therapy for Obstructive Sleep Apnea (OSA)

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In order for Medicare to cover continuous positive airway pressure (CPAP) under our current NCD, Publication 100-03, Medicare National Coverage Determinations Manual, section 240.4, an individual must have obstructive sleep apnea (OSA) as demonstrated by polysomnography done in a facility-based sleep study laboratory. We received a request to expand the current NCD to allow other diagnostic tests to be used to diagnose OSA. Based upon our review, the Centers for Medicare & Medicaid Services (CMS) has determined the following: The evidence is not adequate to conclude that the use of unattended portable multi-channel sleep testing with a minimum of 7 monitored channels including EEG, EOG, EMG, ECG or heart rate, airflow, respiratory effort, and oxygen saturation (Type II Devices based on the 1994 ASDA classification) is reasonable and necessary in the diagnosis of OSA and these tests will remain noncovered for this purpose. The evidence is not adequate to conclude that the use of unattended portable multi-channel sleep testing with a minimum of 4 monitored channels including ventilation or airflow, heart rate or ECG, and oxygen saturation (Type III Devices based on the 1994 ASDA classification system) is reasonable and necessary in the diagnosis of OSA and these tests will remain noncovered for this purpose

Decision Memo: To: Administrative File: CAG 00093R, Continuous Positive Airway Pressure (CPAP) Therapy for Obstructive Sleep Apnea (OSA) From: Steve E. Phurrough, MD, MPA Director, Coverage and Analysis Group Louis B. Jacques, MD Director, Division of Items and Devices LCDR Tiffany Sanders, MD Lead Medical Officer Division of Items and Devices Francina Spencer Lead Analyst Division of Items and Devices James Rollins, MD, PhD Medical Officer Division of Items and Devices Jackie Sheridan-Moore Analyst Division of Items and Devices Subject: Decision: CPAP Therapy for OSA Date: April 4, 2005 I. Decision In order for Medicare to cover continuous positive airway pressure (CPAP) under our current NCD, Publication 100-03, Medicare National Coverage Determinations Manual, section 240.4, an individual must have obstructive sleep apnea (OSA) as demonstrated by polysomnography done in a facility-based sleep study laboratory. We received a request to expand the current NCD to allow other diagnostic tests to be used to diagnose OSA. Based upon our review, the Centers for Medicare & Medicaid Services (CMS) has determined the following: The evidence is not adequate to conclude that the use of unattended portable multi-channel sleep testing with a minimum of 7 monitored channels including EEG, EOG, EMG, ECG or heart rate, airflow, respiratory effort, and oxygen saturation (Type II Devices based on the 1994 ASDA classification) is reasonable and necessary in the diagnosis of OSA and these tests will remain noncovered for this purpose. The evidence is not adequate to conclude that the use of unattended portable multi-channel sleep testing with a minimum of 4 monitored channels including ventilation or airflow, heart rate or ECG, and oxygen saturation (Type III Devices based on the 1994 ASDA classification system) is reasonable and necessary in the diagnosis of OSA and these tests will remain noncovered for this purpose II. Background On April 8, 2004, CMS began a national coverage determination process for the diagnosis of patients with obstructive sleep apnea (OSA) requiring continuous positive airway pressure (CPAP) therapy. Current national coverage guidelines specify that only polysomnography done in a facility-based sleep study laboratory be used to identify patients with OSA requiring CPAP (National Coverage Decision Manual Section 240.4) (Formerly CIM 60-17). CMS has received a request from Dr. Terence M. Davidson, MD, of the University of California San Diego, School of Medicine to modify this decision to include the use of portable multi-channel home sleep testing devices as an alternative to facility-based polysomnography in the evaluation of OSA. Sleep apnea refers to a collection of conditions and syndromes that are characterized by periods of apnea, a temporary cessation of breathing. It was initially described in the early 1800's. One of the first accounts was written by Charles Dickens in 1837 and entitled The Posthumous Papers of the Pickwick Club . Subsequently, William Osler in 1918 coined the term "Pickwickian" to describe the obese, hypersomnolent patient. Over the years, various sleep apnea syndromes have been described and classified into three main types: central, obstructive, and mixed. Central sleep apnea refers to apnea syndromes with origins in the central nervous system. Obstructive sleep apnea (OSA) refers to apnea syndromes due primarily to collapse of the upper airway during sleep. Mixed apnea refers to apnea with both central and obstructive characteristics. Of the three main types of apneas, OSA has received the most scientific interest and study. The prevalence of OSA in the United States has been estimated to be about 2-4% of middle aged adults. 1 OSA has also been identified as a risk factor for other medical conditions including hypertension, nocturnal cardiac arrhythmias, cerebrovascular accidents, and myocardial infarctions. 2 The pathogenesis and pathophysiology of OSA have been studied extensively. During sleep, the upper airway becomes occluded, resulting in an episode of apnea. As a result of the apnea, the patient experiences a brief arousal from sleep. With the return of breathing, the patient typically returns to sleep quickly. This sequence occurs repeatedly. The pharynx has been identified as the primary site of obstruction in most patients. A number of anatomical and functional factors, such as negative oropharyngeal pressure, decreased muscle activity, and possible narrowing of the oropharyngeal lumen may also be involved in the collapse of the upper airway during sleep. Symptoms of OSA include somnolence, fatigue, irritability, headaches, cognitive impairment, depression, and personality changes. 3 There are a number of medical and surgical treatment options for OSA. 4 Nonpharmacologic medical treatments include education regarding sleep hygiene, weight reduction, tongue-retaining devices, positive airway pressure modalities such as continuous positive airway pressure, and bi-level positive airway pressure (BiPAP). CPAP involves the administration of air usually through the nose by an external device at a fixed pressure to maintain the patency of the upper airway. Medications that may be used in OSA include oxygen, protriptyline and theophylline. Surgical procedures include uvulopalatopharyngoplasty, somnoplasty and tracheostomy. Laboratory based polysomnography, with continuous overnight monitoring of various neurophysiologic and cardiorespiratory parameters of sleep, has been the mainstay in the diagnostic work-up for persons suspected of having OSA. Polysomnography monitors sleep stages, respiratory effort, oxygen saturation, heart rate, body position, and limb movements. From the collected data, measurements such as the apnea hypopnea index (AHI) can be calculated and used to diagnose specific sleep disorders. While the occurrence of apnea has remained a primary diagnostic criterion for sleep apnea, episodes of reduced ventilation have received considerable attention and clinical consideration since the 1980's. The term hypopnea has been used to describe these episodes of reduced breathing; however, there was no general consensus for the definition of hypopnea at the time. 5 Variations in the definition of hypopnea still persist today. Despite such variations, the apnea-hypopnea index (AHI = number of episodes of apneas and hypopneas per hour of sleep) has been utilized extensively in recent years in the published literature in the definition of OSA. The AHI has also been called the respiratory distress index (RDI). Over the past several years, a number of portable devices have been developed that measure to varying extents similar neurophysiologic and cardiorespiratory parameters of sleep as those obtained with laboratory based polysomnography. In 1994, the American Sleep Disorders Association developed a classification system for these devices. Type I devices are considered standard laboratory-based polysomnography. Type II devices are comprehensive portable polysomnographic devices with a minimum of seven channels which measure the same neurophysiologic and cardiorespiratory parameters of sleep as standard polysomnography. These devices allow for the measurement of sleep staging. Type III devices have a minimum of four channels and measure only cardiorespiratory parameters of sleep. Because these devices do not permit the determination of sleep versus wakefulness, abnormal breathing events are calculated as “events per hour in bed” instead of “events per hour of sleep.” Type IV devices measure only one or two respiratory parameters such as oxygen saturation or airflow. III. History of Medicare Coverage In 1986, the CMS (then known as the Health Care Financing Administration) requested the Office of Health Technology Assessment (OHTA) to conduct an assessment of the safety, clinical effectiveness and use of CPAP. OHTA reported that "the consensus of clinical opinion from the available information appears to be that CPAP can in the majority of cases prevent OSA and provide substantial clinical improvement with minimal associated morbidity." They went on further to recommend that "the use of CPAP be covered under Medicare when used in adult patients with moderate and severe OSA who have failed to obtain relief from other non-invasive therapies and for whom surgery would be the only other therapeutic alternative." 6 The diagnosis of OSA required at least 30 episodes of apnea, each lasting a minimum of 10 seconds, during 6-7 hours of sleep. These specifications were based predominately on expert opinions at the time. 7 Based on the OHTA technology assessment, Medicare issued an NCD (see NCD Manual 240.4) which covered CPAP for adult patients with moderate or severe OSA for whom surgery is a likely alternative (effective date January 12, 1987), and adopted OHTA's recommendations on the diagnosis of OSA. Since the 1986 decision specifically addressed CPAP only, the Durable Medical Equipment Regional Carriers (DMERCs) have issued a respiratory assist devices regional medical review policy (RAD RMRP) that addresses BiPAP devices and other accessories (last revised in 1999). Specifically for the treatment of OSA, a respiratory assist device with bilevel pressure capability, without backup rate feature, used with noninvasive interface will be covered for the first three months of noninvasive positive pressure respiratory assistance (NPPRA) if the following criteria are met: complete facility-based, attended polysomnogram has established the diagnosis of obstructive sleep apnea, and single level device (CPAP) has been tried and proven ineffective. Unattended home sleep study testing has been under review by CMS since 1989. The latest review occurred in 1995. In 1995, the agency’s reviewing body for the development of national coverage determinations (formerly the Technical Advisory Committee) concluded that the safety and effectiveness of home studies used to diagnosis sleep disorders was unproven and thus should not be covered by the Medicare program. The TAC recommended that this issue be reconsidered for national policy following the completion of a large study of sleep disorders by the NIH. This was to include an evaluation of in-home testing. The study was expected to be completed within two to three years. Therefore, the coverage of unattended home sleep study testing was left to carrier discretion. Medicare is a defined benefit program. An item or service must fall within a benefit category as a prerequisite to Medicare coverage: § 1812 (Scope pf Part A); § 1832 (Scope of Part B); § 1861(s) (Definition of Medical and Other Health Services). CMS considers diagnostic testing to be the appropriate coverage category for multichannel home sleep testing. Section 2055 of the Medicare Carriers Manual covers diagnostic services to diagnose conditions such as sleep apnea in a sleep clinic facility. Although this device is meant to be used in the patient’s home, the physician uses the results of multichannel home sleep testing as a diagnostic tool to determine the patient’s course of treatment. The clinical findings are simply a component of the diagnostic system that assists the physician in managing a patient’s care. In 2001 the national coverage policy on CPAP was expanded to include Medicare beneficiaries with an apnea/hypopnea index (AHI) of ≥ 15, or an AHI ≥ 5 and ≤ 14 with documented symptoms of excessive daytime sleepiness, impaired cognition, mood disorders or insomnia, or documented hypertension, ischemic heart disease or history of stroke. However, the guidelines specified that only a polysomnography done in a facility-based sleep study laboratory could be used to identify patients with obstructive sleep apnea. IV. Timeline of Recent Activities Date Action April 8, 2004 Request posted and the beginning of the initial 30-day comment period on this NCD for scientific input relevant to the issue under consideration. April 13, 2004 A Benefit Category Determination (BCD) was requested from the Center for Medicare Management (CMM). May 27, 2004 The BCD was approved by CMM. June 25, 2004 Comments from the initial comments period were posted. The public was invited to participate in a second 30-day period. Comments were requested on the following questions: How does the diagnostic test performance of unattended portable multi-channel home sleep testing compare to facility-based polysomnography in the diagnosis of obstructive sleep apnea? If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea which parameters of sleep and cardiorespiratory function (i.e. sleep staging, body position, limb movements, respiratory effort, airflow, oxygen saturation, ECG) are required? If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea what conditions (i.e. patient education, technician support) are required so that it is done correctly in the home? July 2, 2004 Requested a Technology Assessment from the Agency for Healthcare Research and Quality. July 29, 2004 Announced the presentation of this issue to the Medicare Coverage Advisory Committee (MCAC). August 27, 2004 Federal Register Notice published announcing MCAC. Instructions for presenters are given in the Federal Register Notice. August 31- June 3, 2004 CMS held multiple meetings with industry representatives. Information from industry representatives, related articles from Medline searches, and public comments were obtained and reviewed. September 2, 2004 The MCAC panel questions posted for review. September 7, 2004 The Technology Assessment Report, second round of comments, and the MCAC Roster posted. September 28, 2004 The issue was presented to the MCAC. January 7, 2005 The Proposed Decision was posted for a 30-Day comment period. February 7, 2005 The comment period closed for the Proposed Decision. V. FDA Status These and other similar devices, such as multi-channel home sleep study testing and other related devices have been considered and cleared for marketing by the Food and Drug Administration (FDA) under a 510(k) process. The 510(k) is a notification of intent to market a specific device. The FDA has determined that certain home sleep study testing devices are "substantially equivalent to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act." A substantially equivalent determination assumes compliance with the Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the FDA will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. Typically, no clinical data is required as part of the 510 (k) application, but instead the clearance process focuses on technical performance. However, the FDA does request clinical data for snore validation as well as event detection (i.e. clinical validation that the apneas or hypopneas detected are also scored as apneas or hypopneas by a manual scorer). The FDA also compares sensitivity and positive predictive values to a predicate device. The FDA has cleared many devices that allow a patient to wear a device that collects airflow and other patient measurements into a device that records data. The patient then takes the device to the physician and the physician downloads information that determines whether the patient has apnea sleep-related breathing disorder including obstructive sleep apnea or needs further sleep studies or assessment. There are currently many sleep assessment devices on the market cleared by the FDA through the 510(k) process for use in the home. VI. General Methodological Principles When 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 is 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) of the Social Security Act.) 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 intervention will improve net health outcomes for patients. The general methodological principles of study design utilized in our review of the evidence are in Appendix B. VII. Evidence Below is a summary of the evidence considered during this national coverage determination process. A. Introduction Consistent findings across studies of net health outcomes associated with an intervention or diagnostic test as well as the magnitude of its risks and benefits are key considerations in the coverage determination process. For this decision memorandum, CMS held a Medicare Coverage Advisory Committee (MCAC) meeting and commissioned an external technology assessment (TA) from the Agency for Healthcare Research and Quality (AHRQ) to review published clinical evidence on the use of unattended portable monitoring devices in the diagnosis of OSA. CMS reviewed information and recommendations provided as a result of the MCAC meeting, the TA provided by AHRQ, and an independent search and review of individual clinical studies addressing this issue. We also received information from professional societies and other groups/organizations, searched evidence based practice guidelines, consensus statements, and position papers. Outcomes of interest for a diagnostic test are not limited to determining its accuracy but include beneficial or adverse clinical effects, such as change in management due to test findings or preferably, improved health outcomes for Medicare beneficiaries. Accuracy refers to the ability of the test to distinguish patients who have or do not have the target disorder when compared to a reference standard. Measures used to determine accuracy include sensitivity (probability of a positive test result in patients with disease) and specificity (probability of a negative test in patients who do not have the disease). In evaluating diagnostic tests based on a reference standard, comparable sensitivity and specificity values would be an outcome of interest. In the absence of direct evidence to show that the diagnostic test under review improves health outcomes, evidence of improved sensitivity or specificity could still prove useful as an intermediate outcome and data point estimate in the construction or a decision. There is no anatomic or physiologic “gold standard” for the diagnosis of obstructive sleep apnea, in contrast to conditions such as cancer where a tissue biopsy result is the definitive standard reference. In studies that compare portable home sleep monitoring to facility-based polysomnography (PSG) performed in a sleep laboratory, the investigators have used the PSG result as the standard reference, i.e. the PSG result is used to define the true disease state for the individual patient. This is less than ideal, but represents the practical difficulty in diagnosing obstructive sleep apnea (OSA). Given the absence of a true “gold standard” reference, the clinical application of terms such as sensitivity and specificity is not straightforward. Such evidence permits only the comparison of home sleep monitoring to facility-based PSG. It is problematic to make the inferential leap from there to a judgment on the ability of home sleep monitoring or PSG to accurately identify those patients who will, if untreated with CPAP, suffer the morbidity and mortality of obstructive sleep apnea. If an individual patient has conflicting results with these two tests, e.g. a negative home test in the face of a positive PSG, there is no available higher reference to determine whether the conflict arises from a false negative home test or a false positive PSG. B. Discussion of evidence reviewed 1. Assessment questions The development of an assessment in support of Medicare coverage decisions is based on the same general question for almost all requests: “Is the evidence sufficient to conclude that the application of the technology under study will improve net health outcomes for Medicare patients?” The formulation of specific questions for the assessment recognizes that the effect of an intervention can depend substantially on how it is delivered, to whom it is applied, the alternatives with which it is being compared, and the delivery setting. In order to evaluate the net health outcomes of using unattended portable multi-channel sleep monitoring devices for the diagnosis of OSA as compared to laboratory based polysomnography, CMS sought to address the following questions: Question 1: How does the diagnostic test performance of unattended portable multi-channel home sleep testing devices compare to facility-based polysomnography in the diagnosis of OSA? a. If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea, which parameters of sleep and cardiorespiratory function (i.e. sleep staging, body position, limb movements, respiratory effort, airflow, oxygen saturation, electrocardiogram) are required? b. If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea, what conditions (i.e. patient education, technician support) are required so that it is done correctly in the home? 2. External technology assessments Systematic reviews are based on a comprehensive search of published studies to answer a clearly defined and specific set of clinical questions. A well-defined strategy or protocol (established before the results of the individual studies are known) guides this literature search. Thus, the process of identifying studies for potential inclusion and the sources for finding such articles is explicitly documented at the start of the review. Finally, systematic reviews provide a detailed assessment of the studies included 8 . 9 CMS commissioned a technology assessment from AHRQ to assess the utility of unattended portable monitoring devices in the diagnosis of OSA. 9, 10 This TA was an update to a systematic review originally published in 2003. 11 The following is a summary of the TA search strategy and findings. Search strategy A search of the MEDLINE database, The Cochrane Library, the National Guidelines Clearinghouse, and the International Network of Agencies for Health Technologies Assessment (INAHTA) database and a hand search of bibliographies included in the articles were conducted. This TA specifically searched for and evaluated literature published since 2002. Filters and limitations were used, and inclusion and exclusion criteria were developed to identify articles to be reviewed. One hundred seventy-two unique titles and abstracts were identified. One hundred fifty-seven articles did not meet inclusion criteria. Fifteen articles were retrieved for full review and 12 met inclusion criteria and were reviewed in detail. Four studies evaluated Type III devices. Only two 12 of these four compared results of portable device studies performed in the home with laboratory based polysomnography. Results and appraisal Three of the four studies evaluating Type III devices were rated as either fair or poor in terms of the quality of the evidence. The percentage of patients with missing data was in the range of 13-18% for unattended home studies. Sensitivities for unattended home studies were 91-95% and specificities were 81-91% for AHI > 15. Sensitivity and specificity values for other AHI cut-off points were noted to be similar. Studies reporting agreement measures such as correlation coefficients or Bland-Altman plots, noted good agreement for results obtained with the portable monitoring devices as compared to polysomnography. Manual scoring of portable monitoring device results was noted to be more discriminate in calculating AHI as compared to automated scoring. The TA authors conclude that most articles only provided information on the use of portable monitoring devices in the laboratory setting when performed simultaneously with polysomnography. These studies do not provide information on the use and performance of portable monitoring devices unattended in the patients’ home. The studies evaluated reported a wide range of data loss results for in home studies. The literature reviewed suggests that data loss appears to be greater when the patient performs set-up of the equipment. Results obtained from automated portable device scoring appear to provide less agreement with polysomnography than does manual scoring. “More evidence is needed to reach conclusions about the effect of co-morbidities, age, patient versus technician performed hookup on the overall effectiveness of home studies in diagnosing OSA compared to in-laboratory PSG.” 3. Internal technology assessments Search Strategy An initial search of the MEDLINE® database was conducted on April 18, 2004. This search was updated on December 2, 2004. Filters and limitations were used, and inclusion and exclusion criteria developed to identify articles to be reviewed. The search used applicable MeSH heading and text words. Articles providing information regarding technical feasibility only were excluded from further review. Articles pertaining to devices that included only 1 or 2 channels of physiologic information to define sleep disordered breathing events (Type IV devices based on the 1994 American Sleeps Disorders Association classification) were also excluded from further review. In addition, the requestor provided abstracts or citations for 26 articles. Articles pertaining to Type IV devices, evaluating the use of auto-titration of CPAP, poster presentations, and those not in the English language were excluded from review. All articles identified and reviewed during our internal technology assessment, were also reviewed as part of the initial or updated external TA. This section summarizes the findings of the systematic review performed by CMS on the use of unattended portable multi-channel home sleep testing devices in the diagnosis of OSA. It includes a summary of the results of 21 articles. For discussion purposes, studies are grouped by device type: (1) those with a minimum of 7 monitored channels including EEG, EOG, EMG, ECG or heart rate, airflow, respiratory effort, and oxygen saturation (Type II Devices based on the 1994 ASDA classification system) and (2) those with a minimum of 4 monitored channels including, ventilation or airflow, heart rate or ECG, and oxygen saturation (Type III Devices based on the 1994 ASDA classification system). Devices that included only 1 or 2 channels of physiologic information to define sleep disordered breathing events (Type IV Devices based on the ASDA classification system) were not considered multi-channel devices and were not reviewed as part of this decision. For a detailed description of each article, refer to the evidence tables provided under Appendix A. Question 1: How does the diagnostic test performance of unattended portable multi-channel home sleep testing devices compare to facility-based polysomnography in the diagnosis of OSA? a. If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea, which parameters of sleep and cardiorespiratory function (i.e. sleep staging, body position, limb movements, respiratory effort, airflow, oxygen saturation, electrocardiogram) are required? b. If unattended portable multi-channel home sleep testing is as effective as polysomnography in the diagnosis of obstructive sleep apnea, what conditions (i.e. patient education, technician support) are required so that it is done correctly in the home? Five studies 13 were reviewed that addressed the diagnostic test performance of portable multi-channel home sleep testing devices with a minimum of seven monitored channels including EEG, EOG, EMG, ECG or heart rate, airflow, respiratory effort, and oxygen saturation. Laboratory based polysomnography was used as the reference standard. The number of participants ranged from 20 to 103. Study participants were predominantly male with a mean age in the range of 45-52. Portier (2000) studied 103 patients referred to a sleep laboratory for work-up of possible OSA. Patients underwent both an unattended portable study in the home and a laboratory based study. Minisomno, the portable device utilized, was described as being able to collect and store 8 hours of data from 10 to 18 channels. Patients came into the sleep laboratory for set-up of the portable device. A total of 26 patients (25%) were excluded from analysis secondary to poor quality of the data. In 21 of these 26 patients (81%) the poor quality data was obtained during the portable device segment of the study. OSA was defined as a respiratory disturbance index (RDI) ≥ 15. Based on calculations from the information provided, the sensitivity and specificity for the portable monitoring study were 81% and 98% respectively. Orr (1994) studied 40 patients, 20 from each of 2 sleep laboratories with portable and laboratory based studies performed simultaneously in the laboratory setting. Sleep I/T, the portable device utilized, was described as an 8 channel device. No results had to be excluded from the analysis secondary to missing or unanalyzable data. Sleep I/T data were analyzed automatically. Based on an RDI ≥ 15, the sensitivity and specificity for the Sleep I/T system were 100% and 93% respectively. Mykytyn (1999) studied 20 male symptomatic patients referred to a sleep laboratory for suspected OSA. Portable and laboratory based studies were performed simultaneously in the laboratory setting. For the portable study, patients were randomly assigned to either an attended or unattended group. Compumedics PS1-Series was the portable device utilized. Outcome measures included determination of AHI, signal quality, derived values such as sleep staging and efficiency, and clinical interpretation of the data by an experienced sleep physician. Using an AHI > 10 as diagnostic of OSA, the sensitivity and specificity of the portable device were 80% and 90% respectively. For the diagnostic cut-off of AHI > 20, the sensitivity and specificity of the portable device were reported as 100% and 100% respectively. Based on the physician’s interpretation of the data, diagnostic concordance was attained in 16 of 18 study pairs (89%). Two portable studies, one attended and one unattended, were deemed insufficient for analysis secondary to poor quality data. The diagnostic interpretation for the 2 discordant pairs were diagnosing OSA versus upper airway resistance and diagnosing moderate versus mild OSA. Two other studies, Iber (2004) and Fry (1998), also compared unattended portable devices with laboratory based PSG. No sensitivity or specificity data were provided. The primary outcome measures included quality of the recordings, reliability of neurophysiologic and cardiorespiratory parameters of sleep, and measurement of RDI obtained using the portable device versus the laboratory based PSG. Iber (2004) reported results as interclass correlational data based on the reproducibility of measurements for RDI when comparing unattended portable studies with laboratory based studies. Twelve participants were excluded from the analysis secondary to poor quality data of either the unattended or laboratory based study. Correlational data showed reproducibility of RDI measurements obtained using the portable device when compared to the laboratory study. Fry (1998) reported results using the Pearson correlation coefficient. All data were interpretable. Correlational data showed a moderate to strong degree of agreement for sleep and respiratory parameters obtained with the portable study when compared to the laboratory study, r values were in the range of 0.775 - 0.999. For portable device studies performed unattended in the home by Portier (2004) and Fry (1998), the authors noted that patients came into the laboratory for education on proper use of the device. In addition, they received assistance with device set-up which could include proper application of the sensors in the Fry study. Portier (2004) also noted that the devices were tested to make sure they were functioning properly. Iber (2004) noted that patients had electrodes attached immediately before sleep. The authors did not provide further information regarding patient education or technician assistance. Sixteen studies were reviewed that addressed the diagnostic test performance of portable multi-channel home sleep testing devices with a minimum of four monitored channels including: ventilation or airflow (at least two channels of respiratory movement or respiratory movement and airflow), heart rate or ECG, and oxygen saturation. Laboratory based polysomnography was used as the reference standard. Three studies 14 evaluated the use of unattended portable monitoring devices in the home setting and compared the results to laboratory based polysomnography. Ancoli-Israel (1997) studied 36 volunteer subjects recruited from a larger study. Patients first underwent an in-home portable study followed by two nights of laboratory polysomnography within one week of the initial study. Patients received in laboratory set-up of the portable device, the Nightwatch System. Data were scored automatically with the ability to manually verify the information. Thirty-four subjects had data available for analysis. Two subjects did not have analyzable dataone during the portable device study and one during laboratory polysomnography. Based on an AHI ≥ 10, the sensitivity and specificity for the portable device were 100% and 63% respectively. Parra (1997) performed a study of 89 patients referred to a sleep clinic for evaluation of OSA. Within a one-month period, patients underwent both laboratory and home based studies. Fifty of 89 patients had technician assistance in setting up the equipment in their home. The EdenTrace system was the portable device utilized in this study. Primary outcome measures were diagnostic agreement, determination of diagnostic usefulness, and clinical decision making. Using the Bland and Altman method for determining diagnostic agreement, agreement was noted in AHI measurements obtained by both study methods. The sensitivity and specificity for the portable device were calculated for various AHI cut-off points10, 18, and 23. Based on polysomnographic AHI > 10 and portable device AHI > 18 and diagnostic of OSA, the sensitivity and specificity for the portable device were 73% and 80% respectively. Based on the same polysomnographic cut-off point and portable device AHI > 23, the sensitivity and specificity for the portable device were 63% and 93% respectively. When comparing portable and laboratory based studies, clinical decision making was the same for 79 (89%) of patients. Of the 10 patients with discordant results, six would not have received CPAP therapy based on the portable study but would have received it based on polysomnography. Whittle (1997) performed a study of patients referred to a sleep clinic for suspected OSA. The two part study consisted of both a validation and prospective trial. The EdenTrace system, the portable device used, was a four channel device. Twenty-three subjects underwent the validation study which included laboratory based polysomnography on the first night, followed by an unattended home study on the second night. Twenty of 23 studies (87%) produced interpretable recordings and were used in data analysis. A significant correlation (r = 0.8) was found when comparing AHI obtained using the laboratory and home based studies. Based on the validation study, an AHI > 30 was chosen as diagnostic of OSA for home based studies. One hundred and forty-nine subjects took part in the prospective trial. Twenty seven of 149 home based studies (18%) were uninterpretable. Patients with an AHI of < 30 based on the home studies and symptoms of daytime sleepiness were further investigated with laboratory based polysomnography. Fifty eight subjects had data from both studies that could be used for comparison. The sensitivity and specificity for the home based study based on an AHI > 30 for the home study and AHI > 15 for polysomnography were 75% and 58% respectively. The authors also performed a control arm of the study that included 75 patients referred to the sleep clinic who only received laboratory polysomnography. Four studies 15 compared the use of unattended portable monitoring devices in the home setting to simultaneous polysomnography and portable monitoring performed in the laboratory setting. Dingli (2003) studied 101 patients referred to a sleep clinic for sleep related complaints. Patients were assigned to two groups. Forty underwent synchronous polysomnography and portable studies in the laboratory. The remaining 61 patients received an in-home unattended study and in-lab polysomnography on separate nights. Patients did receive technician instructions on how to operate the equipment in the sleep clinic prior to taking the device home. The portable device utilized was the Embletta system. Results for the synchronous study excluded one patient because no data was recorded on the Embletta system. Eleven of 61 (18%) of home study patients were excluded from analysis secondary to inadequate recordings. Based on polysomnography scoring AHI ≥ 15 as diagnostic of OSA and Embletta scoring of (A+H) x hrs in bed ≥ 20, the Embletta system had an accuracy of 100% (23/23) for identifying persons with disease. Based on the Embletta system, nine patients were classified as not having OSA with (A+ H) x hrs in bed ≤ 10 and all of these patients had polysomnography AHI ≤ 15. Therefore, the diagnostic accuracy for determining persons without disease was 100% (9/9). Eighteen patients (36%) were classified as possibly having OSA based on the Embletta system and (A+H) x hrs in bed ≥ 10 but ≤ 20 and would likely have required additional testing for definitive diagnosis. Fifteen of these 18 patients would have been diagnosed as having OSA based on polysomnography. The sensitivity and specificity were not explicitly stated for the Embletta system but were calculated as 61% and 75% respectively. Reichert (2003) studied 51 patients referred to a sleep laboratory for clinical suspicion of OSA. Patients underwent simultaneous polysomnography and attended portable device studies in the laboratory. Patients also underwent 3 nights of separate unattended home recordings and the average AHI across the 3 nights of studies were used for results. Forty-five patients had data that were used in the analysis. AHI ≥ 15 was used as diagnostic of OSA for both polysomnography and the portable device. Six percent (3/48) of patients did not have interpretable data secondary to problems with the portable monitoring device in the home setting. Thirteen percent (7/51) of patients did not have data from the portable monitoring device in the laboratory setting due to technician error or data loss. The sensitivity and specificity for the attended portable device studies were 95 ± 5% and 91 ± 6% respectively. The sensitivity and specificity for the unattended portable device studies in the home setting were 91 ± 6% and 83 ± 8% respectively. The authors also compared sensitivity and specificities for the attended and unattended use of the device. The sensitivities for attended in lab use and unattended at home use were 94 ± 5% and 89 ± 7% respectively. The specificities for attended in lab use and unattended at home use were 90 ± 6.7% and 80 ± 8.9%. White (1995) studied 100 patients referred for evaluation of sleep related complaints. Thirty patients underwent simultaneous portable studies and polysomnography in the laboratory setting. Seventy patients underwent laboratory based polysomnography and an additional portable study in the home setting. The Nightwatch System, the portable device utilized, has the capability to transmit signals in real time to the sleep laboratory. Throughout the night, if problems with the signal were identified by the lab technician, patients were telephoned and instructed on how to correct the problem. Two (2.8%) home studies were excluded from analysis secondary to lack of interpretable data. Eighty-one percent (57/70) of participants required a phone call by the technician to correct equipment or signal problems. The sensitivity and specificity of the portable device when used in the lab were provided for two different AHI cut-off points. For AHI > 10, the sensitivity and specificity were 100% and 64% respectively. Positive and negative predictive values were 87% and 100% respectively. For AHI > 20, the sensitivity and specificity were 77% and 88% respectively. Positive and negative predictive values were 83% and 83% respectively. The sensitivity and specificity for the portable device when used at home for AHI > 10 were 91% and 71% respectively. Positive and negative predictive values were 87% and 84% respectively. For AHI > 20, the sensitivity and specificity were 86% and 83% respectively. Positive and negative predictive values were 79% and 89% respectively. Redline (1991) studied 51 subjects including a mix of healthy volunteers, relatives of apnea patients, persons with sleep related complaints, and patients with pulmonary disorders. Results were reported for 20 subjects who underwent simultaneous portable studies and laboratory based polysomnography and 5 subjects who underwent separate unattended portable studies and laboratory based polysomnography. RDI was noted to be highly correlated (r = 0.96) when comparing devices. Using an RDI ≥ 10 by PSG as diagnostic of OSA, 95% (20/21) patients would have been accurately diagnosed by the portable study. Studies performed by Parra (1997), Dingli (2003), Reichert (2003), and White (1995) detailed the methodology used for unattended portable device set-up. Fifty of 89 patients in the Parra study had the technologist set-up the equipment. The remainder of the patients was provided written instructions and 10 minutes of technician instruction. Dingli (2003) also provided education to patients in the form of written instructions. However, patients were responsible for unsupervised equipment setting in their homes. In the Reichert study patients were given written instruction and no other form of assistance with device set-up. The device used included a voice alert system that would awaken patients and alert them if any of the sensors became dislodged during the night. In the study by White, all of the patients came into the laboratory for instructions on proper use of the device. The majority also had the device hooked-up while they were in the laboratory. This device also transmitted signal information back to the laboratory in real-time. At the start of the study, the laboratory could confirm that the device was working properly. In addition, throughout the course of the night the technician could contact the patient to correct any signaling or equipment problems. Nine additional studies 16 evaluated the results of various portable monitoring devices used simultaneously with laboratory based polysomnography. Each study involved the use of various endpoints including Apnea Index (AI), Apnea Hypopnea Index (AHI), and/or Respiratory Distress Index (RDI). Sample sizes ranged from 29 to 150 participants. For these studies the average participant age was 52. Most studies involved the use of consecutive patients referred to sleep lab for evaluation. Only two studies, Claman (2001) and Verse (1998), included information about inclusion and exclusion criteria. In all nine studies, type III devices and PSG were performed simultaneously in the laboratory setting and an attendant was present for all studies. No studies were performed in the home setting. In the study by Calleja (2002), the unattended mode was selected for use in portable monitoring device. All other studies, when dealing with type III devices, made no mention of operating in an unattended mode. In all of the studies the technician placed the sensors for both the type III devices and PSG. One study noted that technicians controlled PSG recordings, and were allowed to fix any failing signals, (Marrone 2002). In this same study, technicians were not allowed to visualize signal recordings from type III devices. If during the study one of the polysomnography sensors malfunctioned or became detached, the technician would correct it. The other studies did not describe how this same problem is addressed for type III devices. Several of the nine studies used measures of agreement such as correlation coefficients or the Bland and Altman analysis to determine the degree of association between endpoints for portable monitoring devices as compared to PSG. Six of the nine studies used Pearson’s correlation coefficients to determine the degree of association between endpoints for both diagnostic modalities. AHI values varied between studies; some defined OSA with an AHI of 10, while other studies used an AHI of 15. Man (1995) reported a correlation coefficient of 97% for AHI between both diagnostic tests, while Claman (2001) reported a correlation of 96% when comparing AHI as the endpoint. Verse (2000), noted a correlation coefficient of 97% when using AI as an endpoint for comparison, while Marrone (2001) noted significant correlation when comparing a number of indices between both diagnostic tests (r between 68% and 99%). Esnaola (1996) noted an intraclass correlation agreement of 72% for AHI between the two diagnostic tests. Another statistical test used to measure the degree of agreement between diagnostic tests was the Bland and Altman analysis. Both the Marrone (2001) and the Ballester (1995) studies showed high levels of agreement for indices between diagnostic tests. Sensitivity and specificity were used by all studies to measure accuracy between both diagnostic procedures (refer to Appendix A). Positive predictive values (PPV) and negative predictive values (NPV) were also reported in some studies. A few studies employed the use of receiver operating characteristic (ROC) curves to determine these measures of accuracy Ballester (1995); Esnaola (1996); and Calleja (2002). Most studies used AHI threshold values ranging from 5 to 30, though two studies; Ficker (2001) and Zucconi (1996); compared AHI values as high as 40. A large number of studies had dichotomous endpoints (e.g., AHI values < 15, or AHI values > 15). One study, Calleja (2002), included five different sets of ranges for AHI values. When reviewing the studies using dichotomous outcomes, one study Claman (2001) reported sensitivity for AHI > 15, but did not report specificity for this same variable. It also reported specificity for AHI < 15, but did not report sensitivity for this variable. Another dichotomous study, Ballester (2000), developed a receiver operating characteristic (ROC) curve to predict accuracy measures using PSG cut-off values. When reviewing these studies with dichotomous values, it is noted that all studies reveal high values for sensitivities as well as specificities. Studies also show high positive predictive values as well as negative predictive values. In general for these studies with dichotomous values, as we move from a lower to a higher AHI value, the sensitivity for this variable either stays the same or increases in value thus indicating a strong accuracy measure compared to PSG in making a diagnosis of obstructive sleep apnea. Also, the corresponding specificity increases in value. This also indicates that agreement exists with PSG in excluding a diagnosis of obstructive sleep apnea. A number of other studies were evaluated comparing PSG with level III devices, using three or more sets of AHI ranges. Two studies, Esnaola (1996) and Zucconi (1996), compared results of manual scoring of AHI to automatic scoring in its comparison to PSG. Both studies consistently demonstrated that manual scoring was superior to automatic scoring. The Esnaola study used changes in heart rate, oxygen saturation, and breathing sounds as indices to identify occurrences of apnea or hypopnea during manual scoring. The study utilized a system of two or three channel manual scoring indices. In the case of the three-channel manual scoring index (MS3), an event was defined as the simultaneous occurrence of changes in all three variables. The two-channel manual scoring index (MS2) defined an event when changes in two of the three variables were identified. Specificity was high for both two and three-channel manual scoring systems, but sensitivity was marginal, especially for the two-channel system. This study also revealed that sensitivity as well as negative predictive value was increased when measuring with a two-channel system as compared to the three-channel system. There is a slight increased positive predictive value for the two-channel system as compared to the three-channel system. The study performed by Zucconi (1996) revealed that even over a large range of AHI scores (10 through 40), all measures of accuracy (sensitivity, specificity, PPV, NPV) using the manual scoring were consistently high indicating close agreement with PSG. Automatic scoring was in agreement with PSG reading until AHI values were high (e.g., AHI > 40). At this level the accuracy in comparison with PSG became poor. Three studies were also of particular interest