A retrospective analysis of 12,036 obstructive sleep apnea patients at a single sleep center finds that two-thirds, 66.3%, have positional OSA (POSA), defined as a supine apnea-hypopnea index at least double the non-supine AHI. Published July 4 in Sleep & Breathing, the study provides one of the largest characterizations of POSA’s clinical and polysomnographic signature to date.
The finding matters because POSA responds differently to treatment than non-positional OSA. Patients whose breathing events cluster in the supine position often benefit from positional therapy, devices or strategies that keep them off their back, which can reduce or eliminate the need for CPAP.
What they found
Researchers analyzed records from all patients who underwent polysomnography at a single center between September 2017 and August 2023. Among the 12,036 diagnosed with OSA, they classified each case as POSA (supine AHI at least twice non-supine AHI) or non-POSA, and further subdivided POSA into supine-predominant (p-POSA) and supine-exclusive (e-POSA).
Key results:
- 66.3% of OSA patients met POSA criteria.
- 27.8% had supine-exclusive OSA (e-POSA).
- POSA patients had substantially lower overall AHI (24.1 vs. 44.4 events/hour, p < 0.001), lower BMI (29.2 vs. 31.4 kg/m2, p < 0.001), and were slightly younger than non-POSA patients.
- No overall sex differences for POSA, but e-POSA was more frequent in women (p < 0.001).
- After adjusting for AHI severity, POSA remained independently associated with shorter sleep and REM latency, longer total sleep time, higher sleep efficiency, more N3 (deep sleep), better oxygenation (higher mean SpO2, lower T90), and lower arousal index (all p < 0.01).
- These differences were more pronounced at lower AHI levels and attenuated with increasing disease severity (significant group x AHI interactions, p < 0.05).
A notable overlap emerged with REM-related OSA: among POSA patients, 32.0% also had REM OSA (REM-AHI at least twice NREM-AHI), and nearly 70% of REM OSA patients exhibited positional dependence. This asymmetry, positional dependence was more common in REM OSA than the reverse, suggests overlapping but distinct mechanisms.
Why it matters
Positional therapy is often underutilized. These data clarify that POSA is the dominant form of OSA, not a niche subtype, and that it has a consistent profile: lower severity, lower BMI, and better sleep architecture independent of AHI. The finding that POSA features are most distinct in mild disease supports early intervention, positional therapy may be most effective when initiated before the condition progresses.
The REM OSA overlap finding is clinically relevant. Patients with REM-predominant OSA who also have positional dependence might respond to a combined positional-sleep-stage approach, rather than defaulting to CPAP.
Limits
Data come from a single sleep center (retrospective design). The center’s population, referral patterns, and diagnostic thresholds may not generalize to other settings. AHI severity cutoffs for defining POSA vary across studies, and the study’s binary classification may oversimplify a continuous spectrum of positional dependence.
Bottom line
Two out of three OSA patients have a strong positional component. The condition is milder, associated with lower BMI, and less disruptive to sleep architecture than non-positional OSA. These findings support wider use of positional therapy as a first-line or adjunct treatment, particularly in patients with less severe disease.
Source: Rosa CFA, Chillcce KAS, Cahali MB, Boldt MS, Soares VHD. Analysis of positional obstructive sleep apnea features in 12,000 patients at a sleep center. Sleep & Breathing. 2026 Jul 4;30(4):207. DOI: 10.1007/s11325-026-03755-3. PMID: 42400703.