Effects of MAFLD defined by fatty liver index or ultrasonography on kidney function decline in the general population.

This study aimed to investigate whether metabolic dysfunction-associated fatty liver disease (MAFLD) defined by the fatty liver index (FLI) affects the decline in kidney function and whether this relationship is still observed in MAFLD defined by ultrasonography (USG). A retrospective cohort study was conducted using de-identified data from participants who received health checkups at Samsung Changwon Hospital between 2002 and 2018. The primary and secondary exposures were the presence of FLI- and USG-defined MAFLD, respectively. The primary outcome was 5-years slope of eGFR. The secondary outcome was a rapid decline in kidney function, defined as a 5-years slope of estimated glomerular filtration rate (eGFR) of less than - 3 mL/min/1.73 m per year. A total of 37,500 participants were included in the analysis. Participants with FLI-defined MAFLD had a larger decline in 5-year eGFR slope than those without FLI-defined MAFLD (beta coefficients - 0.11; 95% CI - 0.14 to - 0.08). Participants with FLI-defined MAFLD had a higher risk of rapid kidney function decline than those without FLI-defined MAFLD (odds ratio 1.33; 95% confidence intervals (CIs) 1.05-1.69). However, USG-defined MAFLD was less related to kidney function decline. In conclusion, the presence of FLI-defined MAFLD was associated with larger and faster kidney function decline.