1102 Association of Rapid Eye Movement Sleep, Oxygen Saturation, AHI Severity, Depression, and Metabolic Syndrome in OSA: A Retrospective Analysis

Abstract Introduction Obstructive Sleep Apnea (OSA) is associated with elevated rates of depression and metabolic syndrome, likely mediated by intermittent hypoxia and sleep fragmentation. Whether these outcomes differ based on respiratory events occurring during REM versus non-REM sleep remains uncertain. This study examines the relationship between REM-related oxygen saturation (SaO₂), AHI severity, depression, and metabolic abnormalities in adults with OSA. Methods A retrospective chart review was conducted on adults with OSA who underwent baseline polysomnography without CPAP therapy. Extracted variables included mean REM SaO₂, total AHI, depression diagnosis, and metabolic syndrome components (hypertension, type 2 diabetes, and hyperlipidemia). Patients who did not enter REM sleep were excluded from REM SaO₂ analyses but retained for descriptive comparison. Linear regression assessed the association between mean REM SaO₂ and total AHI. Independent t-tests compared mean REM SaO₂ across diagnoses of depression, hypertension, type 2 diabetes, and hyperlipidemia. Results Of 250 patients reviewed, 35 (14%) did not reach REM sleep. Among the 215 patients who achieved REM sleep, lower mean REM SaO₂ significantly predicted higher total AHI (β = –3.18; p < 0.001). Mean REM SaO₂ did not differ by depression (p = 0.35) or hyperlipidemia (p = 0.19) but was significantly lower in patients with type 2 diabetes (p < 0.01) and hypertension (p < 0.001). Compared with REM-capable patients, those who failed to reach REM exhibited more severe OSA (mean AHI 40 vs 23) and higher rates of depression (40% vs 33%), hyperlipidemia (77% vs 40%), type 2 diabetes (37% vs 20%), and hypertension (71% vs 46%). Conclusion Mean REM SaO₂ is strongly associated with AHI severity in patients with OSA. While REM SaO₂ was not associated with depression or hyperlipidemia, its significant relationship with hypertension and type 2 diabetes highlights possible links between REM-related desaturation and cardiometabolic burden. Individuals who failed to reach REM sleep had more severe OSA and a greater prevalence of all comorbidities. Prospective studies including larger proportions of patients with severe OSA are needed to further define these associations. Support (if any)