The Fatty Liver Index's Association with Incident Chronic Kidney Disease in Korean Middle-Aged Adults: A Community-Based Cohort Study

(1) Background: The relationship between nonalcoholic fatty liver disease (NAFLD) and incident chronic kidney disease (CKD) is unclear, and long-term follow-up data are limited. Therefore, this study aimed to evaluate whether NAFLD, as assessed by the fatty liver index (FLI), could predict the development of CKD in a community-based Korean cohort over 16 years. (2) Methods: Among the 10,030 total participants, 7778 patients without CKD were selected from the Korean Genome and Epidemiology Study (KoGES). The FLI grade ranged from 0 to 100 and was divided into three groups: low (FLI, <30), intermediate (FLI, 30-59), and high (FLI, >= 60). An estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m(2) or the development of proteinuria was considered to indicate incident CKD. (3) Results: During the 16-year follow-up period, 919 individuals (11.8%) developed CKD. The HRs of incident CKD in the intermediate FLI group (30-59) and high FLI group (>= 60) increased compared with the reference low FLI group (<30) after adjusting for potentially confounding variables. NAFLD, as assessed by the FLI, was an independent risk factor for CKD. (4) Conclusions: Our findings suggest that the FLI, a simple surrogate biomarker of fatty liver disease, may be used to identify people at high risk of incident CKD in clinical practice.