Sarcopenia and Physical Function in Obstructive Sleep Apnea: A Single‐Centre Cross‐Sectional Study (The SOSA Study)

INTRODUCTION: Whether obstructive sleep apnea (OSA) severity is independently associated with sarcopenia, beyond the effects of age, obesity and sex, has not been established in a single-centre cohort using standardised ultrasound-based assessment. We examined sarcopenia prevalence and its components across OSA severity strata in a Kuwaiti cohort using the ISarcoPRM sarcopenia algorithm. METHODS: Cross-sectional within-cohort analysis of 110 adults aged 50 years or older with confirmed OSA (apnea-hypopnea index AHI 5 or more events/h by Level 3 portable monitoring; SomnoTouch, Somnomedics, Germany), stratified as mild (AHI 5-14.99, n = 28), moderate (AHI 15-29.99, n = 39) or severe (AHI 30 or more, n = 43). Sarcopenia was assessed using the ISarcoPRM algorithm: quadriceps muscle thickness by ultrasound, Sonographic Thigh Adjustment Ratio (STAR), handgrip strength (Jamar dynamometer) and chair stand test (CST). RESULTS: Demographic and comorbidity profiles were balanced across severity groups (all p > 0.05). Quadriceps muscle thickness, STAR and handgrip strength did not differ significantly across severity strata (all Kruskal-Wallis p > 0.05). CST time showed a significant gradient across severity strata (Kruskal-Wallis p = 0.047), and both AHI and ODI correlated modestly with CST time (r = +0.209, p = 0.029 and r = +0.203, p = 0.034, respectively). Sarcopenia prevalence was 21.4%, 30.8% and 34.9% in mild, moderate and severe OSA, respectively, with no significant trend (Cochran-Armitage p = 0.237). Age (OR 1.12 per year, 95%CI 1.05-1.19, p < 0.001) and BMI (OR 1.10 per kg/m2, 95%CI 1.02-1.18, p = 0.009) were the independent predictors of sarcopenia; OSA severity was not (adjusted OR 1.19, 95%CI 0.65-2.18, p = 0.577). Low STAR prevalence was 83.6%, driven by the high-obesity burden in this cohort and the origin of STAR cut-offs in a lower BMI Turkish reference population. CONCLUSION: In this Kuwaiti OSA cohort, age and BMI are the dominant determinants of sarcopenia, with no independent contribution from OSA severity. A modest association between OSA severity indices and CST time suggests that physical function may be more sensitive to OSA-related changes than muscle mass per se. The near-universal low STAR prevalence points to the need for population-specific normative data in high-obesity cohorts.