Comparative associations of non-alcoholic fatty liver disease and metabolic dysfunction-associated steatotic liver disease with risk of incident chronic kidney disease: a cohort study

We examined the comparative associations between non-alcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated steatotic liver disease (MASLD) definitions with risk of developing chronic kidney disease (CKD) and abnormal albuminuria. We conducted a cohort study of 214,145 Korean adults with normal kidney function at baseline who underwent liver ultrasonography. Participants were further subdivided into no steatotic liver disease (no-SLD), NAFLD-only, MASLD-only, both NAFLD and MASLD, and SLD not categorized as NAFLD or MASLD groups. Cox proportional hazards models were used to analyze the risk of incident CKD and albuminuria. Compared with either the no-NAFLD or no-MASLD groups, the NAFLD and MASLD groups were associated with a higher risk of incident CKD (NAFLD: adjusted hazard ratio (HR), 1.18 [95% CI, 1.01-1.38]; MASLD: adjusted HR, 1.21 [95% CI, 1.04-1.39]). Among the five subgroups, both NAFLD and MASLD group had the strongest association with risk of incident CKD (adjusted HR, 1.21 [95% CI, 1.04-1.42]). The MASLD-only group had the strongest association with incident abnormal albuminuria, with an adjusted HR comparable to that of the both NAFLD and MASLD group (adjusted HR 1.96 [95% CI, 1.44-2.67] for the MASLD-only, and adjusted HR 1.98 [95% CI, 1.58-2.49] for the both NAFLD and MASLD group versus the no-SLD group). The NAFLD-only group was not independently associated with risk of CKD or abnormal albuminuria. These findings suggest that MASLD definition identifies individuals at high risk of developing incident CKD or abnormal albuminuria better than NAFLD definition.