Low creatinine-to-body weight ratio predicts incident MASLD and MetALD in Japanese adults: a cohort study

Metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic and alcohol-related/associated steatotic liver disease (MetALD) are major public health concerns. Although low muscle mass, also known as sarcopenia, is a potential risk factor for these conditions, simple markers are needed for risk stratification. The creatinine-to-body weight (Cr/BW) ratio has been identified as a surrogate marker for relative muscle mass. This study investigated the association between the Cr/BW ratio and the incidence of MASLD/MetALD in Japanese. This retrospective cohort study included 22,453 Japanese adults (45.4% men; mean age, 44.6 years) who underwent health checkups between 2015 and 2024. Participants without MASLD/MetALD at baseline were followed up. The Cr/BW ratio was categorized into sex-specific quartiles (Q1–Q4). Cox proportional hazards models were used to calculate hazard ratios (HRs) for MASLD/MetALD development. Over a median follow-up of 2.99 years, 2,424 men (23.8%) and 1,332 women (10.9%) developed MASLD/MetALD. After multivariable adjustment, a higher Cr/BW ratio was significantly associated with a lower incidence of MASLD/MetALD. Compared with the lowest quartile (Q1), the highest quartile (Q4) was associated with an HR of 0.370 (95% CI, 0.327–0.420) in men and 0.172 (95% CI, 0.142–0.207) in women. This inverse association remained significant across most subgroups stratified by age, body mass index (BMI), estimated glomerular filtration rate, and alcohol intake. A low Cr/BW ratio was an independent predictor of MASLD and MetALD development in Japanese adults. The Cr/BW ratio may serve as a simple, non-invasive marker for identifying individuals at high risk for these increasingly prevalent liver diseases.