Obstructive sleep apnea is associated with greater MASH and significant fibrosis severity in patients with obesity: A prospective clinicopathological study

Background Epidemiological studies have shown an association between obstructive sleep apnea (OSA) and metabolic dysfunction‐associated steatotic liver disease (MASLD), yet the precise role of OSA in MASLD severity remains unclear. We aimed to evaluate the association of OSA with liver histological severity in Chinese bariatric surgery patients, especially metabolic dysfunction‐associated steatohepatitis (MASH) and significant fibrosis. Methods This prospective cross‐sectional study enrolled 582 consecutive bariatric surgery patients. Key exclusions were other liver diseases, significant alcohol intake, and prior OSA treatment. All participants underwent preoperative polysomnography and intraoperative liver biopsy. Patients were stratified by biopsy‐proven MASLD severity and OSA severity (apnea‐hypopnea index, AHI). The primary outcomes were the associations of OSA with histologically defined MASH and significant fibrosis (stage ≥2). Results More severe MASLD subtypes exhibited higher AHI and greater hypoxia ( p < 0.05). OSA severity was positively associated with histological features, including steatosis, ballooning, lobular inflammation, and fibrosis (all p < 0.05), as well as with higher NAFLD activity score (NAS) ( p < 0.001) and MASH activity grade ( p < 0.001). Multivariable analysis identified OSA as an independent predictor associated with histologically confirmed MASLD (odds ratio [OR] 1.86, 95% confidence interval [CI], 1.08–3.22), lobular inflammation (OR 95%CI, 1.18–2.79), MASH (OR 95%CI, 1.09–2.71), and significant fibrosis (OR 95%CI, 1.49–7.08). A linear dose–response relationship existed between AHI and both MASH and significant fibrosis ( p < 0.05). Conclusions OSA is associated with more severe histological features of MASLD and contributes to the severity of MASH and significant fibrosis in patients with obesity.