411 REM predominance of OSA: Associated with supine position, but not with CPAP adherence

Abstract

Abstract Introduction Obstructive sleep apnea (OSA) is a heterogeneous disease dependent on many factors including the sleep stage and the body position. OSA is often more severe during the rapid eye movement (REM) sleep stage, a phenomenon known as REM predominance. Prior studies suggested associations of higher REM predominance of OSA with younger age, higher obesity, and lower adherence to continuous positive airway pressure (CPAP) therapy, but these studies had small cohort sizes. Here we leverage home-based sleep tests (HST) that estimate REM sleep and measure body position to study REM predominance in a larger cohort of OSA patients. Methods We retrospectively reviewed patients who took HST at our clinic using devices based on peripheral arterial tonometry (WatchPAT, Itamar Medical). The HST results included estimated REM sleep periods and measured body positions. Auto-titrating CPAP therapy was prescribed for the majority of OSA patients diagnosed by the HST. Our inclusion criteria were: apnea-hypopnea index (AHI) above 5 /hour, estimated REM sleep time above 30 minutes, oxygen saturation below 90% (T90) for less than 10 minutes, and successful retrieval of CPAP usage data. CPAP adherence was defined as the percentage of nights with CPAP usage above four hours, and REM predominance as the ratio between REM AHI and non-REM AHI. Additionally, the percentage of estimated sleep time in supine position was calculated. Results Among 292 consecutive patients whose HST were reviewed, 113 patients met the inclusion criteria. The 25th-75th percentile ranges of age, body mass index (BMI), AHI, REM predominance, CPAP adherence and supine sleep percentage were 36–56 years, 28.1–38.4 kg/m2, 8.9–25.9 /hour, 1.27–2.89, 40%-97% and 28%-72%, respectively. REM predominance was not associated with CPAP adherence (P > 0.05), but was significantly associated with lower age, higher BMI, and higher supine sleep percentage (all P < 0.01). Conclusion We found that REM-predominant OSA is relatively more prevalent not only in young and obese patients, but in patients who sleep relatively more in the supine position. This association of REM predominance with body position is a novel finding to our knowledge. Contrary to prior studies, we did not find association of REM predominance with adherence to CPAP therapy. Support (if any):