Clinical characteristics and outcomes of positional obstructive sleep apnea: the sleep heart health study

Positional obstructive sleep apnea (POSA) is common among obstructive sleep apnea (OSA) patients and exhibits distinct clinical features. This study aimed to analyze the clinical characteristics and associated factors of POSA, as well as compare the outcomes between POSA and non-POSA (NPOSA).

OSA subjects aged over 40 years from the Sleep Heart Health Study were included in this study. OSA was classified into POSA and NPOSA according to the Cartwright criteria. Univariate and multivariable logistic regression analyses were conducted to identify predictors of POSA. The incidence of outcome events across the two groups was assessed using cumulative hazard curves and compared with the log-rank test.

A total of 1,080 OSA subjects were included, with 412 in the NPOSA group and 668 in the POSA group. In the univariate analysis, body mass index, diabetes, apnea-hypopnea index (AHI), the percentage of sleep time with oxygen saturation below 90% (CT90) and arousal index were inversely associated with POSA, average oxygen saturation during sleep and minimum oxygen saturation during sleep were positively associated with POSA. In the multivariate analysis, AHI (OR 0.98, 95% CI 0.97 to 0.99, p = 0.006) and CT90 (OR 0.98, 95% CI 0.96 to 1.00, p = 0.027) remained significantly inversely associated with POSA after adjusting for other variables. There was no significant difference in the cumulative hazard of myocardial infarction, stroke, congestive heart failure, or all-cause mortality between the two groups during the mean follow-up period of 11 years.

This study identified AHI and CT90 as independent predictive factors for POSA. There was no significant difference in the incidence of myocardial infarction, stroke, congestive heart failure, or all-cause mortality between POSA and NPOSA.