To determine the prevalence of positional obstructive sleep apnea (POSA) and exclusive POSA (ePOSA) in the general population and to assess the factors independently associated with POSA and ePOSA according to gender and menopausal status.
Participants of the population-based HypnoLaus Sleep Cohort underwent full polysomnography at home. POSA was defined as an apnea-hypopnea index (AHI) ≥5/h, and supine/non-supine AHI ratio (sAHI/nsAHI) ≥2 (ePOSA when non-supine AHI was normalized).
In this study, 1719 subjects (40-85y.o. 46% men) with at least 30 min spent in both the supine and non-supine positions were included. OSA was present in 1224 subjects (71%) (AHI >5/H). POSA was present in 53% of all subjects, and in 75% of OSA subjects. ePOSA was present in 26% of all subjects and in 36% of OSA subjects. In multivariate analyses, lower AHI and lower BMI were both associated with POSA and ePOSA in males. In premenopausal females, no single factor was associated with POSA while a lower AHI and an Epworth sleepiness scale >10 were associated with ePOSA. In postmenopausal women, a lower BMI was associated with POSA and a lower AHI and a lower Mallampati score with ePOSA.
In this large population-based study, we found that POSA is present in 53% of the middle-to-older age general population, and in 75% of OSA subjects. ePOSA was present in 36% of OSA subjects, suggesting that a large proportion of them could be treated with positional therapy. AHI and BMI were differently associated with POSA in men, and pre or post-menopausal women.