Analysis of positional obstructive sleep apnea features in 12,000 patients at a sleep center

This study aimed to determine the prevalence of Positional Obstructive Sleep Apnea (POSA) and evaluate clinical and polysomnographic characteristics.

Retrospective analysis of patients undergoing polysomnography (September 2017-August 2023), classified as POSA or non-POSA and as supine-predominant (p-POSA) or supine-exclusive (e-POSA).

Among 12,036 patients with OSA, 66.3% had POSA and 27.8% had e-POSA. Compared with non-POSA, POSA patients had lower AHI (24.1 vs. 44.4 events/h, p < 0.001), lower BMI (29.2 vs. 31.4 kg/m², p < 0.001), and were slightly younger. No sex differences were observed for POSA, although e-POSA was more frequent in women (p < 0.001). After adjustment for AHI, POSA remained characterized by shorter sleep and REM latency, longer total sleep time, higher sleep efficiency, greater proportion of N3, improved oxygenation (higher mean SpO₂ and lower T90), and lower arousal index (all p < 0.01). NREM oxygen saturation and total arousals were not significantly different. Significant group × AHI interactions (p < 0.05) indicated that these differences were more pronounced at lower AHI levels and attenuated with increasing severity. Among POSA patients, 32.0% had REM OSA (REM-AHI ≥ 2× NREM-AHI), while nearly 70% of REM OSA exhibited POSA.

POSA is highly prevalent and characterized by lower BMI and a more favorable sleep and oxygenation profile independent of AHI. Differences in POSA, although small, were more evident in milder disease and diminished with increasing severity. The overlap with REM OSA was asymmetric, with positional dependence more frequent in REM OSA than the converse. These findings highlight the heterogeneity of POSA and need for individualized management.