Polysomnographic Phenotype of Positional Obstructive Sleep Apnea.

Background and Objectives: Obstructive sleep apnea (OSA) is a prevalent sleep disorder characterized by recurrent upper airway obstruction, leading to disrupted sleep and various health complications. Positional OSA (POSA) refers to patients whose OSA severity is significantly influenced by body position, especially when lying supine. This study aimed to evaluate the polysomnographic characteristics of POSA and non-positional OSA (non-POSA) and to assess their clinical implications. Methods: This retrospective study included patients diagnosed with OSA who underwent type 1 polysomnography. Patients were categorized into POSA and non-POSA groups based on whether their apnea-hypopnea index (AHI) in the supine position was at least twice as high as that in the lateral position. We collected and analyzed clinical and polysomnographic parameters, including AHI, oxygen desaturation index, arousal index, nadir peripheral oxygen saturation (SpO Results: In total, 500 patients with OSA were analyzed, of whom 63.4% were classified as having POSA. Patients with POSA exhibited milder disease severity than those without, with an average AHI of 23.3±15.3/h versus 43.9±27.9/h, respectively, and a higher nadir SpO Conclusion: Patients with POSA generally exhibited milder disease and more favorable polysomnographic profiles than non-POSA patients. POSA is prevalent in mild-to-moderate OSA, and identifying it via polysomnography may inform tailored treatment strategies.