Relevance of cortical arousals for risk stratification in sleep apnea: a three cohort analysis.

STUDY OBJECTIVES: There is uncertainty on best approaches for defining apnea-hypopnea events. To clarify the contributions of desaturation vs arousal to defining hypopneas, we examined the associations of events with desaturation (≥3%) but not arousal (AHI≥3%Only ) versus events with arousals but no desaturation (AHIArOnly ) with obstructive sleep apnea (OSA)-related comorbidities and incident cardiovascular disease (CVD) across multiple cohorts.

METHODS: In the Sleep Heart Health Study (SHHS, N=5473), the Multi-Ethnic Study of Atherosclerosis (MESA, N=1904), and the Osteoporotic Fractures in Men Study (MrOS, N=2685), we examined the independent associations of AHI≥3%Only and AHIArOnly with hypertension, diabetes, and daytime sleepiness, and incident CVD.

RESULTS: After adjusting for covariates and AHI based on events with EEG arousal (regardless of desaturation), AHI≥3%Only was associated with hypertension in SHHS (Odds Ratio, OR: 1.12; 95% confidence interval: 1.04,1.21), per 1SD increase). Similar associations were observed in MESA and MrOS, as well as for associations with diabetes (OR: 1.30; 1.09,1.54 and 1.25; 1.07,1.47, respectively), sleepiness (OR: 1.19; 1.00,1.41 and 1.17; 1.01-1.35), and incident CVD (hazard ratio: 1.37; 1.05,1.77 and 1.14; 1.00,1.29). In contrast, after adjusting for events with desaturation (regardless of arousal), AHIArOnly was unassociated with these outcomes. In SHHS, greater baseline OSA severity was associated with a reduction in arousal frequency over 5 years (p<0.0001).

CONCLUSIONS: In middle-aged and older individuals, addition of events with arousals does not improve the strength of associations with comorbidities or incident CVD. Research is needed to understand generalizability to younger individuals and the mechanistic role of arousals in OSA.