Metabolic Dysfunction-Associated Fatty Liver Disease Increases the Risk of CKD in a Young to Middle-Aged Population

Background: Patients with liver disease have a higher prevalence of chronic kidney disease (CKD) than those without. Metabolic dysfunction–associated fatty liver disease (MAFLD) has recently been identified as a lifestyle-related disease; however, its association between with CKD development remains unclear. This study investigated whether MAFLD is associated with CKD development in a young to middle-aged population. Methods: This retrospective observational study utilized annual health checkup data from Japanese individuals aged 20–60 years, collected between 2009–2014. Participants with an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2 at baseline were excluded. CKD development was defined as having an eGFR of <60 mL/min/1.73 m2 five years later. The FIB-4 score was calculated using age, AST and ALT levels, and platelet count. A FIB-4 score of ≥1.30 was considered high. MAFLD was diagnosed using the fatty liver index (FLI)—calculated from body mass index, waist circumference, and triglyceride and γ-GTP levels—in combination with obesity, metabolic disorders, or diabetes mellitus. The primary outcome was the development of CKD after five years, analyzed using logistic regression following propensity score matching. Results: Of the 11,296 individuals initially recruited, 4,822 (90.6 % male) met the eligibility criteria. Mean age and baseline eGFR were 44.7 years and 77.8 mL/min/1.73 m2, respectively. CKD developed in 9.6% of participants. The prevalence rates of MAFLD and high FIB-4 scores were 35.3% and 9.2%, respectively. The FLI was not correlated with the FIB-4 score (r=−0.02, P=0.14). Receiver operating characteristic curve analysis indicated that the FIB-4 score (AUC=0.61, 95% CI: 0.59–0.64) was a better predictor of CKD development than the FLI (AUC=0.55, 95% CI: 0.52–0.58). After propensity score matching, MAFLD was found to be a significant risk factor for CKD development (coefficient=0.039, 95% CI: 0.014–0.064, P=0.002), whereas a high FIB-4 score was not (coefficient=0.016, 95% CI: −0.033 to 0.065, P=0.529). Conclusion: MAFLD was a significant risk factor for CKD development five years later in a young to middle-aged population; however, the FLI was not a better predictor than the FIB-4 score.