Until 2009, when Center for Medicare and Medicaid Services (CMS) approved home sleep monitoring, the diagnosis of obstructive sleep apnea (OSA) was made primarily through in-laboratory polysomnograms (PSG).1 OSA, a common disorder characterized by partial or complete collapse of airway during sleep, is associated with increased cardiovascular co-morbidities, risk for motor vehicle crashes, and decreased quality of life.2,3 The prevalence of OSA continues to rise with the increase in obesity epidemic as strong association has been found between the two. The Wisconsin sleep cohort study reported a prevalence of 2% to 4% among women and men respectively.4 Another study estimated that one in four American adults is at high risk for OSA.5
Despite being labor intensive, technically complex, and expensive, polysomography (Type 1 study) is still considered the gold standard of diagnosis. Since it requires an overnight stay in a laboratory, some patients also find it uncomfortable and inconvenient. Many individuals still remain undiagnosed in part because of lack of adequate resources or due to the high costs associated with the diagnosis and treatment. In last two decades, efforts at increasing accessibility and reducing healthcare expenditures have led to the emergence of alternative modalities for diagnosing and treating OSA. Thus, there has been an exponential increase in portable sleep testing driven mainly by the imperative to decrease the cost of diagnostic testing primarily from in-laboratory polysomnograms.
In 2007, an AASM task force recommended use of portable devices for diagnosing OSA among patients with high pre-test probability6 and without co morbidities. Type 3 portable devices with at least four channels (airflow, respiratory movements, heart rate, and oxygen saturation) were proposed in this recommendation. Subsequently, CMS approved the use of unattended type 2, 3 or even 4 monitors for diagnosing OSA and for prescribing continuous positive airway pressure (CPAP). Of the available portable devices, Type 3 is most commonly used. Studies have validated type 3 monitoring devices with acceptable sensitivity and specificity.7 However, these studies may underestimate the AHI as sleep variables are lacking.
Continuous positive airway pressure (CPAP) is the standard treatment for patients with OSA,8,9 and heretofore has required a laboratory polysomnogram with pressure titration. The goal is to obtain an optimal pressure for eliminating apneas, hypopneas, and snoring during all sleep stages and body positions. CPAP has been shown to have beneficial effects on several outcome measures such as blood pressure, and daytime sleepiness. However fixed pressures can lead to high mask leaks, and reduced PAP compliance remains a concern. To potentially address this problem, auto titrating devices were developed. In contrast to CPAP, auto titrating positive airway pressure (APAP) devices deliver varying pressure based on individual patient's needs. These varying pressures theoretically lead to an increase in breathing synchrony with CPAP, and could improve patient comfort and thus enhance positive airway pressure (PAP) adherence. A Cochrane review in 2009 comparing APAP with CPAP, found APAP slightly more efficacious than CPAP in increasing patient compliance.10 Moreover, the need for attended titration is eliminated, potentially reducing the costs. In a recent meta-analysis the effects of APAP versus CPAP in short term changes in AHI, quality of life, and most other sleep measures were similar among moderate to severe OSA patients without significant co morbidities.11
In this issue Berry and Sriram12 prospectively compared the effectiveness of APAP treatment after patients are diagnosed with OSA by a home sleep study (HST) to fixed pressure CPAP after an in-laboratory titration. The authors state that in carefully selected patients there was no significant difference in adherence, subjective sleepiness, or quality of life between the two pathways. Participants in both groups had moderate to severe OSA with an average ESS 14 to 15, and were followed closely through phone calls and clinic visits in order to identify and rectify any problems. The study demonstrated that average 90% nightly pressure in APAP group was slightly lower than the PSG PAP group; however the results did not reach statistical significance. Similarly, nightly use was higher among APAP arm participants, but again without statistical significance. Interestingly, despite a similar residual AHI in both groups, PAP satisfaction was higher in APAP group (p < 0.05). Moreover, significant improvement was noted in ESS and FOSQ in both groups (p < 0.001), and did not differ between the two groups. Another interesting finding of this study is that the time from diagnosis to treatment was significantly shorter in APAP group (50.4 ± 38 versus 78 ± 33 days, p < 0.001).
However we should be cautious in interpreting the results of this study. As the authors point out, these findings cannot be generalized since the study enrolled a primarily middle aged, older, and predominantly male veteran affairs (VA) population. In contrast to the non-VA sector of patients, intense durable medical equipment support was provided by the study's Veterans Affairs hospital eliminating out of pocket expense to the patients, thereby possibly resulting in improvement in adherence. Another limitation of the study is a low response rate for enrollment leading to the possibility of volunteer bias. Among the patients approached for study participation, only 22% expressed interest. Irrespective of these limitations, Berry and Sriram12 have made an important contribution and provide further validation for the use of APAP without an in-laboratory PAP titration in patients diagnosed with moderate to severe OSA using a HST. However, future studies are needed to determine whether this paradigm will be applicable to “real world” patient care settings other than the VA.
Dr. Quan is Editor-in-Chief of the Journal of Clinical Sleep Medicine. Dr. Batool-Anwar has indicated no financial conflicts of interest.
Batool-Anwar S, Quan SF. To auto-titrate or not auto-titrate: is the question answered? J Clin Sleep Med 2014;10(12):1277-1278.
Decision Memo for Sleep testing for Obstructive Sleep Apnea (OSA) CAG-00405N. Accessed October, 2014.
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