April 10, 2007
Steve Phurrough, MD
Director of Coverage and Analysis Group
Centers for Medicaid and Medicare Services
7500 Security Boulevard
Baltimore, MD 21224-1850
Dear Dr. Phurrough,
The American Academy of Sleep Medicine (AASM) appreciates the opportunity to comment on the CMS review of its national coverage decision (NCD) on CPAP therapy for obstructive sleep apnea (OSA).
The AASM is the professional organization for the specialty of Sleep Medicine. The Academy represents 5,061 physicians who practice in this specialty and 1,078 other health care providers, and 1,169 accredited sleep centers and laboratories. The AASM publishes practice guidelines, diagnostic criteria, and other clinical practice papers to help provide “best care” for patients in Sleep Medicine, accredits sleep centers and laboratories, and has been the moving force behind the formal recognition of the specialty by the Accreditation Council on Graduate Medical Education. We are also a major provider of medical education in sleep for sleep specialists, other health care providers and the public.
We commend CMS for its wisdom in adhering to scientific evidence for determining national coverage decisions. The AASM has also been committed to the development of practice guidelines based on evidence based medicine in order to assure the best possible care of patients with sleep disorders. In this response, we will cover the question of availability of laboratory polysomnography in the United States, summarize the data on portable monitoring available up to 2004, analyze more recent studies germane to the topic, discuss some of the wider implications of a change in the NCD to include portable monitoring, describe current initiatives of the AASM in the area of portable monitoring and comment on the suggestion to alter the “two hour rule”. We will emphasize that OSA is a chronic disease needing a comprehensive approach to its diagnosis, investigation and long-term management and that this should be done in AASM accredited sleep facilities or by board certified sleep specialists to provide the most optimal and cost-effective service to patients.
Laboratory Polysomnography is Widely Available in the United States
Dr. Nielsen contends several times in his letter, without providing any evidence, that the diagnosis of patients with sleep disordered breathing is limited by laboratory polysomnography (PSG) “not (being) widely available.” While this might be the case in some countries, this statement is not supported by data that look at the availability of sleep laboratories across the United States. A study based on 2001 data estimated that 427 PSG were performed per year per 100,000 population (J Clin Sleep Med 2005; 1:23-26). Since 2001, the number of sleep laboratories accredited by the AASM has more than doubled to 1,169 with 129 applications having been received in just the first three months of 2007. The graph below illustrates this dramatic growth as sleep medicine specialists have established facilities to evaluate and care for patients.
In a survey by the AASM conducted in 2004 there was an average wait of about three weeks for a sleep study or sleep consultation. An independent survey by Shariq estimated there were more than 2,500 accredited and non-accredited sleep laboratories in the U.S. in 2004 with an average wait time for a PSG between 2 and 3 weeks (Sleep 2005;28:145-6). A 2005 survey of U.S. sleep centers by Wachovia Securities found that in the prior year there was a 27% increase in sleep laboratory bed capacity and a decrease in wait times to 3.9 weeks. A survey of accredited sleep laboratories completed by the AASM in April 2007 indicated that the wait time for a PSG has been reduced to a median of 12 days and that the wait time for a sleep consultation has fallen to a median of 14 days.
Thus, in contrast to the assertions of Dr Nielsen, there is no evidence to suggest that in the United States as a whole patients have unacceptable delays in accessing sleep consultations or laboratory PSGs. On the contrary, the wait time is shorter than the wait time in many areas for other medical procedures. Furthermore, the number of accredited sleep centers continues to grow and current data suggest that increasing demand will be met by appropriate increased supply.
Previous Analyses Have Not Recommended the Use of Unattended Portable Monitoring for the Diagnosis of Sleep Apnea
In 2003, the AASM, in association with the two major organizations representing pulmonary specialists, the American College of Chest Physicians (ACCP) and the American Thoracic Society (ATS), published “Practice Parameters for the Use of Portable Monitoring Devices in the Investigation of Suspected Obstructive Sleep Apnea in Adults.” (Sleep 2003;26:907-913) In this paper, clinical evidence was graded on 51 studies following the method of a 1997 review by the Agency for Healthcare Research and Quality (AHRQ). Evidence was graded according to a standardized process and recommendations were based on levels of evidence. In particular, there were four published studies that compared multichannel unattended monitoring without EEG to facility-based polysomnography. In these studies, home monitoring showed highly variable and often low specificity for a correct diagnosis of sleep apnea, with varying degrees of false-positive results that ranged as high as 31% of those testing positive. Based on these limited data showing highly variable and questionable performance, the published joint guideline of the three societies did not recommend portable monitoring for diagnosing obstructive sleep apnea.
This AASM/ ACCP/ ATS paper was updated in a September 1, 2004 report commissioned by the Agency for Healthcare Research and Quality. The conclusions of this government sponsored report were “This newer body of evidence does not materially change earlier findings regarding in-home devices for diagnosing OSA.” No new evidence was found that would support a change from the findings of the original joint report that unattended portable monitoring was not recommended for diagnosing obstructive sleep apnea.
While Recent Studies Provide Some Support for Portable Monitoring in Selected Populations Managed in Academic Centers, They Do Not Warrant a Current Change in CMS Policies
In this section we discuss the three more recent studies cited by Dr Nielsen in his letter, as well as the 2007 study by Mulgrew et al. It should be noted that all four studies were performed outside the United States in countries with very different health care systems and access to laboratory PSG. All studies were performed in academic health centers by specialists in sleep medicine and the results cannot be extrapolated to primary care or surgical practices.
The study by Senn et al (Chest 2006;129:67-75) does not assess portable monitoring at all. It is a study of 76 highly selected sleepy snorers, chosen from 195 patients with cardiopulmonary co-morbidities, other disorders that might explain sleepiness, nasal obstruction or previously diagnosed sleep disorders excluded. Patients were arbitrarily placed on auto-adjusting CPAP for 2 weeks with success defined as > 2 hours CPAP use per night and patients’ willingness to continue CPAP therapy. Forty of the 76 patients required subsequent PSG and thus only 36 of the original 195 patients (18%) might have avoided a sleep study. Of these, one was shown not to have OSA at all, despite the patient perceiving the empiric treatment to be successful.
The study of Hukins et al (Am J Respir Crit Care Med 2005;171:500-5) also does not assess portable monitoring. All patients had proven OSA, diagnosed during a night of laboratory PSG. Forty five, without comorbidities or serious nocturnal hypoxemia, commenced arbitrary pressure CPAP therapy for 3 months; 6 patients (13%) discontinued CPAP during this time. The authors argue that this protocol allowed them to identify patients who could not tolerate CPAP and thus would have wasted resources by undergoing a second night titration study. However, an equally valid explanation is that the use of empiric arbitrary pressure CPAP may have resulted in poor compliance as the system may have been set to incorrect pressures from the start. In addition, most patients in the United States undergo a combined single night diagnostic and therapeutic study, resulting in cost saving and improved access for other patients.
The study of Whitelaw et al (Am J Respir Crit Care Med 2005;171:188-93) compared the outcome of a group of tired patients with a history suggestive of OSA who underwent laboratory PSG with a similar group who underwent home monitoring. Initial screening reduced a group of 4,767 potential patients to 2,088; of these 439 were randomly selected. A further 85 (19%) were excluded from this already attenuated group because of lack of sleepiness, presence of comorbidities or “significant physiologic consequences of OSA.” After 2 weeks use of auto-titrating CPAP, a further home monitoring study was performed and additional adjustments made. There was no difference at 4 weeks between quality of life indicators, Epworth Sleepiness Score and compliance rates. However, objective compliance rates were low in both groups (mean nightly use of 3.8 hours for the PSG group versus 3.3 hours for the home monitoring group), potentially related to the use of auto-titrating CPAP. This study suggests that there may be a role for portable monitoring in a highly selected group of OSA patients managed in an academic setting by specialists in sleep medicine with intense follow up including a 2 nd night of portable monitoring after initiation of therapy.
The study of Mulgrew et al (Ann Intern Med 2007;146:157-66) compared the outcome of 35 patients diagnosed by laboratory PSG with 33 diagnosed by portable monitoring. Patients were carefully selected to ensure a high pre-test probability of moderate to severe OSA; patients on sedatives or with major cardiorespiratory or psychiatric diseases were excluded. The portable monitoring group underwent home CPAP auto-titration followed by oximetry after which a fixed CPAP pressure was set, while the control group underwent a second PSG for CPAP titration. Quality of life measures were identical between the 2 groups after 12 weeks while compliance was slightly higher in the portable monitoring group (6 versus 5.4 hours). This study suggests a role for portable monitoring in a carefully selected group of patients with a high probability of moderate to severe OSA who are intensively followed in an academic center by experts in sleep medicine. However, the number of subjects was small and no cost analyses were performed.
In summary, two recent studies provide some evidence in support of portable monitoring for the diagnosis of OSA in selected patient groups with high pre-test probabilities of OSA who are managed intensively in academic centers by sleep specialists. The results cannot be extrapolated to primary care or surgical practices. Further studies are needed to confirm these results and to determine whether these approaches are cost-effective as compared to laboratory polysomnography. They do not warrant a change in the CMS National Coverage Determination.
Sleep Apnea should be Diagnosed and Managed by Sleep Specialists in Accredited Sleep Facilities: Indiscriminate Use of Portable Monitoring Will Result in Increased Costs and Decreased Patient Benefit
OSA should be diagnosed by a combination of clinical history, physical examination and recording of patients’ sleep. Such a comprehensive approach by physicians trained and experienced in sleep medicine is necessary to avoid over diagnosis of the condition and unnecessary treatment, as well as to determine the presence of other sleep disorders that may substantially contribute to the patients’ symptoms. The follow up of patients after sleep studies is equally important. Patients should receive a diagnosis of OSA from a sleep specialist experienced in providing different options for therapy with thorough explanations of the advantages and disadvantages of each. OSA is a chronic disorder and patients should be followed in an accredited sleep medicine facility or by a physician board certified in sleep medicine. Without such follow up, compliance with expensive therapies is likely to be poor. This was illustrated by a national survey published last year which demonstrated that patients who were evaluated and treated by board certified sleep specialists at accredited sleep centers had superior outcomes (J Clin Sleep Med 2006;2:133-142).
It is essential that sleep studies be read and interpreted by specialists trained and experienced in their use and this is especially true for portable monitoring studies. According to the 2004 AHRQ report, the overall proportion of home studies with inadequate data due to artifact and sensor displacement averaged 13% and data loss was as high as 33% when the patients performed the hookup. The rate of false positive studies has been estimated at up to 31% and false negative studies at up to 45%. In addition, many of these devices use automated scoring systems to provide a diagnosis which, in general, are more subject to artifact error than is human visual analysis. Furthermore, the use of automated analytic techniques may reduce the likelihood that a physician will actually view the raw data to evaluate its quality.
Because of all these factors, the use of such devices by physicians and surgeons untrained in their appropriate use and especially in the visual analysis of the raw signal that is required in order to properly validate the data, will result in a significant proportion of serious misdiagnoses. This will be compounded if such health care providers do not have the skills to interpret the study results in terms of the patient’s individual clinical sleep history. The result of indiscriminant availability of reimbursement for portable monitoring will be (1) over diagnosis of OSA in many patients followed by inappropriate and costly use of CPAP and surgery and (2) under diagnosis of OSA in many patients, resulting in the need for the increased expense and inconvenience of repeat studies in a laboratory. In a recently published study, using over 1200 patient profiles in four different treatment settings, the authors conclude that portable monitoring actually costs more, in part because it is often necessary to repeat testing with portable monitoring due to technical difficulties or lost data (Sleep Medicine Clinics, 2006; 465-473). Additionally, a meta-analysis by Ghegan et al in 2006 (Laryngoscope 2006;116(6):859-64) reviewed 27 studies comparing portable monitoring and in-laboratory polysomnography. The investigators showed that the lower costs of portable monitoring compared to in-laboratory studies are at least partially offset by the increased number of poor recordings during portable monitoring that would require repeat testing. Interestingly, the investigators also found that the theoretical advantage of better sleep for the patient in his or her own bed did not appear to be the case with recorded sleep time significantly higher in the laboratory studies. In addition, investigators in 2000 (Am J Respir Crit Care Med 2000;162:814-8) found that of 233 patients who were asked their preferences regarding home vs. in-laboratory studies, about twice as many patients (48% vs. 28%) preferred the in-laboratory study since the equipment was less cumbersome and they felt less anxious and safer in the laboratory environment. Thus, some of the presumed advantages of portable monitoring, especially with respect to costs and patient preference, may be questionable.
It is our position that, if portable monitoring is to be used in the future for diagnosis of OSA, it should be restricted to studies performed in AASM accredited sleep facilities or by sleep specialists board certified in sleep medicine. Only in this way will it be certain that patients are receiving comprehensive, appropriate and cost effective care.
The AASM sponsored Multicenter Study of Portable Monitoring Will Assess Both Clinical and Economic Outcomes
The AASM is currently taking a proactive leadership position in assessing the role of portable monitoring. An expert task force, under the leadership of Dr Nancy Collop, is preparing a new practice parameter based on recent publications. The AASM is partnering with the ATS , the ACCP and the European Respiratory Society to hold a workshop entitled “Research Priorities in Portable Monitoring.” Most importantly, the American Sleep Medicine Foundation (an affiliate of the AASM) has issued a request for proposals to conduct a large, multicenter trial that will compare portable monitoring followed by auto-titrating CPAP with laboratory polysomnography and fixed pressure CPAP. This study (see attached protocol) will be unique in that it will examine both clinical and economic outcomes, following a paradigm designed to mimic actual practice scenarios. A scientific review panel is completing review of the proposals and the research group selected to perform the study will be announced shortly. Once this decision is made, the investigation will proceed independent of the AASM to avoid any possible conflict of interest. The AASM strongly suggests that any decisions regarding portable monitoring be delayed until after the results of this landmark study become available.
A Modification of the 2 Hour Rule May be Beneficial to a Minority of Patients with Severe Sleep Apnea
The current national coverage determination is based on an apnea-hypopnea index (AHI) recorded during a minimum of two hours of sleep. This criterion allows adequate studies to be performed for the majority of patients with sleep apnea. However, there exists a minority of patients with severe sleep apnea who have such disrupted sleep with so many arousals from respiratory events that it is difficult to obtain 2 hours sleep in the first half of the night under a split-night protocol and occasionally even with a full night diagnostic study. For these patients, a modification of the criteria may be appropriate to allow for single night studies with a diagnostic portion followed by a CPAP titration portion to be performed.
The AASM would be supportive of a change in the criteria to read: "...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 (i.e. the AHI may not be extrapolated or projected). If the actual number of apneas and hypopneas recorded is 30 or more, then less than 2 hours sleep is acceptable, as long as at least 2 hours polysomnographic recording in bed has been obtained.” The addition of a requirement for 2 hours time in bed would allow for attempts to record both REM and non-REM sleep as well as time in the supine and non-supine positions, thus reducing the probability of false positive and negative results. It would also allow for longer monitoring of the ECG and for greater chance of detection of other potential sleep disturbances, such as periodic limb movements.
The AASM is aware that there are no available data to estimate what proportion of patients would be impacted by such a change in strategy, whether such a change would be cost effective, or whether it would affect outcomes. Thus, while we are supportive of this modification of criteria, we recognize that this is based on expert consensus regarding the welfare of a minority of patients and not on published evidence.
The AASM requests CMS not to alter its NCD on CPAP therapy for OSA to allow diagnosis based on portable monitoring. This request is based on the following considerations:
- Available data indicate that laboratory polysomnography is widely available in the United States and that the widely quoted opinion that there are inadequate numbers of facilities in the nation as a whole is essentially a myth. There is no evidence to suggest that a change in the NCD policy for portable monitoring will have a significant effect on patient access.
- There is strong consensus that published studies up to 2004 have not provided evidence in support of portable monitoring for the diagnosis of OSA. Two recent studies provide some evidence in support of portable monitoring in highly selected cases managed intensively in academic sleep centers, but more research is needed, especially with regard to economic as well as clinical outcomes.
- Available data do not indicate that portable monitoring is more cost effective than laboratory polysomnography, especially taking into account technical failures, as well as false negative and false positive results from portable monitoring.
- Wide use of portable monitoring by physicians and surgeons not trained in its use or in the comprehensive management of patients with sleep disorders will likely result in adverse patient outcomes. There is credible evidence that patients managed for OSA at accredited sleep centers have better outcomes.
- The AASM-sponsored multicenter trial of portable monitoring that is about to commence will provide highly useful data on both clinical and economic outcomes.
If portable monitoring is demonstrated in the future to be of utility in the management of some patients suspected of having OSA, we contend that it will be necessary that such procedures be restricted to use in accredited sleep centers in order to ensure optimal patient care.
Finally, with respect to the “two hour rule”, we support a modification as discussed in detail above, recognizing that this suggested change is based on expert opinion rather than objective evidence.
Thank you for allowing us the opportunity to comment on this highly important issue. We would be very willing to provide any further clarifications that may be helpful to CMS.
Michael H. Silber, M.B.Ch.B.