CPAP will be covered under Medicare in adult patients with OSA under new criteria

In 1986, the Health Care Financing Administration, now known as the Centers for Medicare and Medicaid Services (CMS), requested that the Office of Health Technology Assessment (OHTA) conduct an assessment of the safety, clinical effectiveness, and use of continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA). 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. OHTA went on 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 noninvasive therapies and for whom surgery would be the only other therapeutic alternative. The diagnosis of OSA required at least 30 episodes of apnea, each lasting a minimum of 10 seconds, during 6 to 7 hours of sleep. These specifications were based predominantly on expert opinions at the time.1

Based on the OHTA technology assessment, Medicare issued a National Coverage Determination that 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)2 have issued a respiratory assist devices regional medical review policy that addresses bilevel positive airway pressure devices and other accessories (last revised in 1999). Specifically for the treatment of OSA, a respiratory assist device with bilevel pressure capability without a backup rate feature that is used with a noninvasive

interface will be covered for the first 3 months of noninvasive positive-pressure respiratory assistance if a complete, facility-based, attended polysomnogram has established the diagnosis of OSA and CPAP has been tried and proven ineffective.

Recent Activities
On May 21, 2000, CMS met with the American Academy of Sleep Medicine (AASM). AASM asked us to revise the national coverage policy and to include allowance for hypopneas in the diagnosis of patients with moderate or severe OSA. On June 4, 2001, CMS received a request for a revised national coverage determination.

On July 24, 2001, CMS met with representatives of the AASM. The organization believes that the current national coverage determination needs to be revised. On August 23, CMS participated in a DMERC teleconference to discuss CPAP issues. On September 4, CMS received additional materials for review from device manufacturers and professional organizations.

Should Hypopnea Be Included?
Since the 1980s, hypopnea has been commonly used as a diagnostic criterion for OSA. Gould et al3 reported that “hypopneas are clinically important” in the consideration of OSA. Whyte et al4 reported that hypopneas can be scored reproducibly and that there was close agreement (a high correlation coefficient) in the number of apneas and hypopneas counted by two independent polysomnographers. Variations in the definition of hypopnea have, however, been common. In 1994, Moser et al5 surveyed 45 accredited sleep laboratories and found that “no two laboratories used the same definition and measures of hypopnea.”

To assess the current evidence on hypopnea in greater detail, MEDLINE (from mid 1998 to September 2001) was searched using the terms hypopnea and OSA. More than 200 studies were found. The literature search was then focused, based on inclusion criteria of English-language publication, human subjects, clinical trials, and Index Medicus journals and exclusion criteria of trials involving medications, children, pregnancy, and cellular-level responses. Fifteen studies met the inclusion criteria, reported specific definitions, and did not meet any of the exclusion criteria.

Although there were no specific randomized, controlled trials that evaluated the validity of using hypopnea as a diagnostic criterion for OSA in terms of health outcomes, the use of hypopnea appears to have been accepted as a current standard of practice. This is apparent in the widespread use of the apnea-hypopnea index (AHI), as documented in the methodology of the relevant trials, although variations in the definition of hypopnea are still found. In addition, the DMERCs have proposed the following definitions: first, apnea is the cessation of airflow lasting 10 seconds, as documented in the polysomnogram; second, hypopnea is a reduction in airflow lasting 10 seconds associated with a fall in oxygen saturation and an arousal from sleep, as documented in the polysomnogram.6

Is there scientific evidence of the effectiveness of bilevel therapy for OSA? To assess the effectiveness of bilevel positive airway pressure, MEDLINE (from 1995 to September 2001) was searched using terms for bilevel positive airway pressure, a specific bilevel system, and OSA. Eighteen citations were found. The literature search was focused using inclusion criteria (English language, human subjects, clinical trials, and Index Medicus journals), and exclusion criteria (trials involving medications, children, pregnancy, and cellular-level responses). One randomized trial met the inclusion criteria and did not meet the exclusion criteria.

In 1995, Reeves-Hoche et al7 randomized 83 patients to either CPAP (n=52) or bilevel support (n=31) to determine whether bilevel therapy achieves better patient comfort and hours of use than CPAP. Of the 83 patients enrolled, 62 completed the 1-year study period. The authors found that patient complaints and effective use were similar in both groups, but that the dropout rate was significantly higher in the CPAP group (P=.003). The authors did note a methodological error in the randomization process that resulted in a skewed distribution. This study did not specifically address the effectiveness of bilevel positive airway pressure in terms of health outcomes.

CMS Analysis
Although there were no specific randomized, controlled trials that evaluated diagnostic criteria for OSA and the use of hypopnea, there were myriad clinical trials concerning CPAP and OSA in general. From this indirect evidence, certain accepted definitions and practices may be identified.

Using the most current clinical trials, it is possible to adopt a set of diagnostic criteria and definitions that are more up to date than the ones used in the 1986 Medicare coverage decision. As in other instances in clinical medicine, the diagnostic criteria for OSA (including AHI) appear to be based more on consensus and standards of practice than on direct evidence from clinical trials. This is illustrated in the gradual change of inclusion criteria in clinical trials over the past few years and the convergence of definitions. The use of hypopnea as a diagnostic criterion has been accepted as a standard of practice.8 The AASM recently proposed a standard definition for hypopnea based on one of the largest trials on OSA, the Sleep Heart Health Study (SHHS).8 In the SHHS, hypopnea was defined as an abnormal respiratory event lasting at least 10 seconds with at least a 30% reduction in thorocoabdominal movement or airflow, as compared with baseline levels, and with at least a 4% oxygen desaturation. This definition incorporates thorocoabdominal movement and desaturation because these two factors have been found to be reproducible and measurable during sleep studies.4 The American Thoracic Society also recommended the same definition of hypopnea. Based on the apparent general consensus, CMS will allow the use of hypopnea to calculate AHI for Medicare coverage of CPAP.

In setting a treatment and coverage threshold based on the AHI, two general situations may be considered: patients who do not have symptoms and patients who have symptoms. For patients who do not have symptoms of OSA, treatment with CPAP may still be considered, given the increased risk of hypertension and related cardiovascular conditions associated with OSA. Three large population-based studies have demonstrated the association between OSA and hypertension. A dose-response relationship between AHI and the risk of hypertension was also reported,9-11 but these studies had limitations in sampling, data collection, and generalizability. For example, unattended home polysomnography was used in the SHHS, but Portier et al12 found that the results of home-based testing may be hampered by missing data or poor-quality data. In studies with very large sample sizes, even small differences in measured outcomes may be found to be statistically significant. In some instances, statistical significance does not necessarily imply clinical significance. Overall, these factors may influence the interpretation of results, especially in borderline or very mild cases of OSA.

Our review of the recent literature suggests that hypertension, with an AHI of 15, is a plausible and clinically important risk (the risk roughly doubling, with wide confidence intervals). The studies are less supportive of a hypertension risk with an AHI of less than 15. Of 20 trials, 15 used an AHI of 15 per hour or higher levels. Most used an AHI threshold, regardless of symptoms. Of the eight studies that reported a severity classification, an AHI of 15 per hour was the lowest value for moderate-to-severe OSA. Overall, CMS concludes that the use of CPAP to treat OSA for patients with an AHI of 15 without symptoms is based on reasonably strong epidemiological evidence that this condition increases the risk of hypertension and cardiovascular morbidity.

For patients with symptoms, three randomized, controlled trials have demonstrated that CPAP improves daytime symptoms and functioning, even for patients with mild OSA (an AHI of 5).13-15 Although there were no studies that evaluated discrete health outcomes such as mortality, daytime symptoms such as sleepiness and functioning are important, since quality of life and personal safety may be significantly affected. In their consensus statement, Loube et al16 also supported CPAP treatment for patients with symptomatic, mild OSA (a respiratory distress index of 5 to 30).

Based on these published studies and supported by several evidence-based professional consensus statements, CMS will revise the current Medicare coverage policy to include updated definitions and diagnostic criteria. Since most studies did not identify a severity scale for OSA but, instead, set an AHI value for treatment with CPAP, CMS will remove the reference to severity levels of OSA for Medicare coverage.

Since both types of devices produce positive airway pressure, bilevel devices have been considered similar to CPAP devices and appear to have similar indications for use.17 Reeves-Hoche et al7 found that bilevel positive airway pressure was similar to CPAP in terms of patient complaints and use, but had less treatment discontinuation (fewer dropouts). This seems to be reflected in current practices, as the use of bilevel support has been reserved for patients who have not responded to (or have not tolerated) standard CPAP.2,16 Since there is insufficient direct evidence of the effectiveness of bilevel therapy in OSA to make a national coverage decision, the coverage of bilevel devices for the treatment of OSA will continue to be determined by the local contractors.

CMS will revise the National Coverage Determination for CPAP for the treatment of OSA to the following: CPAP will be covered under Medicare in adult patients with OSA if either of the following criteria is met:

  • AHI of 15, or
  • AHI of 5 to 14 with documented symptoms of excessive daytime sleepiness, impaired cognition, mood disorders, or insomnia, or documented hypertension, ischemic heart disease, or history of stroke.

The AHI is equal to the average number of episodes of apnea and hypopnea per hour and must be based on a minimum of 2 hours of sleep recorded by polysomnography using actual recorded hours of sleep (AHI may not be extrapolated or projected). The polysomnography must be performed in a facility-based sleep study laboratory, and not in the home or in a mobile facility.

Sean Tunis, MD, MSc, is director, Coverage and Analysis Group; Jeffrey Shuren, MD, JD, is director, Division of Items and Devices; Francina C. Spencer is a health insurance specialist, Division of Items and Devices; Joseph Chin, MD, MS, is a medical officer, Division of Medical and Surgical Services; and Jacqueline Sheridan is a technical advisor, Division of Items and Devices, all at Medicare.

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