Muscle and Fat Composition in OSA: A CT-Based Study

Background: Obstructive sleep apnea syndrome (OSAS) is associated with altered body composition, including increased fat accumulation and potential reductions in muscle quality. Sarcopenic obesity—a condition marked by simultaneous muscle degradation and adiposity—is of growing concern in OSAS populations. Methods: We conducted a retrospective study evaluating thoracoabdominal CT scans of 71 OSAS patients and 34 age- and sex-matched controls. Erector spinae muscle thickness and subcutaneous fat were measured at the L1 vertebral level. Associations with clinical markers such as BMI, CRP, and oxygen saturation were examined. Results: OSAS patients had significantly greater muscle thickness and subcutaneous fat compared to controls (p < 0.01). Muscle thickness was positively correlated with BMI and waist circumference but inversely associated with CRP and oxygen saturation. Despite structural hypertrophy, these findings suggest impaired muscle quality and support the presence of sarcopenic obesity in OSAS. Conclusions: CT-based imaging provides valuable structural insights but may overestimate muscle function, particularly in obese OSAS patients. These results highlight the need to integrate imaging with functional assessments to accurately diagnose sarcopenia and guide individualized management strategies.