Do positional and non-positional obstructive sleep apnoea differ clinically? A further comparison of supine-isolated and supine-predominant subgroups.

Abstract

Introduction: Obstructive Sleep Apnoea (OSA) is a heterogeneous disorder characterized by recurrent upper airway obstructions during sleep. Positional OSA (POSA) and non-positional OSA are major subgroups that differ in clinical, polysomnographic, and treatment aspects. Furthermore, POSA can be classified into supine-isolated POSA (siPOSA) and supine-predominant POSA (spPOSA), which exhibit distinct characteristics. This study compares POSA and non-POSA patients, as well as siPOSA and spPOSA subgroups, focusing on their clinical, demographic, and polysomnographic differences.

Materials and methods: This retrospective observational study included patients who underwent polysomnography (PSG) in a tertiary care hospital between 2007 and 2021 due to suspected sleep-breathing disorders. Patients were classified into POSA and non-POSA groups, with POSA further divided into siPOSA and spPOSA subgroups. POSA was defined as an AHI at least twice as high in the supine position compared to other positions. siPOSA included patients with a non-supine AHI < 5 events/h, whereas spPOSA included those with a non-supine AHI > 5 events/h. Demographic, anthropometric, and PSG parameters were compared.

Results: Among 2390 OSA patients, 884 were siPOSA, 519 spPOSA, and 987 non-POSA. POSA patients were younger (50.7 vs. 52.9 years, p < 0.001), had lower BMI (30.6 vs. 34.8 kg/m², p < 0.001), and milder OSA severity compared to non-POSA. spPOSA patients showed higher AHI and more severe OSA than siPOSA (p < 0.001).

Conclusion: POSA represents a milder subgroup compared to non-POSA, and siPOSA is milder than spPOSA. Identifying these subgroups enables tailored, patient-specific treatment approaches, enhancing therapeutic outcomes.