Association between Metabolic Dysfunction-Associated Steatotic Liver Disease and Obstructive Sleep Apnea: A Nationwide Retrospective Cohort Study

Obstructive sleep apnea (OSA) and metabolic liver disease share overlapping mechanisms, yet the association between metabolic dysfunction-associated steatotic liver disease (MASLD) and OSA remains unclear. We conducted a nationwide retrospective cohort study using data from the Korean National Health Insurance Service (NHIS). Adults aged ≥40 years who underwent health screening in 2009–2010 were categorized into four groups: (1) no steatotic liver disease (SLD) and no cardiometabolic risk factors (CMRFs); (2) no SLD with CMRFs; (3) MASLD without alcohol; and (4) MASLD with alcohol and MetALD. Incident OSA was identified using ICD-10 codes. Cox proportional hazards models and restricted cubic spline analyses were applied. Among 265,452 participants (mean age 58.9 years; 52.3% men), MASLD was independently associated with increased OSA risk (adjusted HR 1.48; 95% CI: 1.16–1.89; p = 0.002), with a slightly higher risk in the MASLD with alcohol and MetALD groups (adjusted HR 1.50; 95% CI: 1.16–1.93; p = 0.002). CMRFs alone were not significantly associated with OSA. Spline analysis showed a nonlinear dose–response relationship between fatty liver index and OSA risk. These findings suggest that MASLD—especially with alcohol involvement—is a significant risk factor for OSA, supporting routine sleep screening in this population.