The association between a non-invasive hepatic fibrosis score and urolithiasis among non-alcoholic fatty liver disease (NAFLD) patients in China: a cross-sectional study

OBJECTIVE: Mounting data now support a strong link between the presence of non-alcoholic fatty liver disease (NAFLD) and an increased risk of urolithiasis. However, little is known on the association between hepatic fibrosis and the risk of urolithiasis among NAFLD patients. Therefore, this study aimed to investigate the prevalence of urolithiasis among NAFLD patients and determine whether the Fibrosis-4 (FIB-4) score, a surrogate marker of hepatic fibrosis, is associated with urolithiasis among NAFLD patients. DESIGN: Cross-sectional studies. SETTING: China. METHODS: A total of 2058 adult patients with NAFLD were included in this study. Logistic regression analysis was used to detect the association between FIB-4 score and urolithiasis. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic value of FIB-4 score for the detection of urolithiasis among NAFLD patients. RESULTS: 200 (9.7%) individuals had ultrasonography-diagnosed urolithiasis among 2058 NAFLD patients. FIB-4 score (OR=1.58; 95% CI 1.06 to 2.31), age (OR=1.11; 95% CI 1.08 to 1.13), obesity (OR=3.16; 95% CI 2.29 to 4.39) and hyperuricemia (OR=3.79; 95% CI 2.67 to 5.36) were independent factors associated with urolithiasis among NAFLD patients. Moreover, a novel algorithm including multiple variables (FIB-4 score, age, obesity and hyperuricemia) showed an area under a ROC curve of 0.813 (95% CI 0.795 to 0.829) for identifying urolithiasis among NAFLD patients. The optimal cut-off value of > −2.23 for the multivariate model provides a sensitivity of 76% and a specificity of 74% for predicting urolithiasis among NAFLD patients. CONCLUSION: Urolithiasis among NAFLD patients is associated with FIB-4 score. Further, a novel algorithm based on FIB-4 score could serve as a useful tool for identifying individuals with a higher risk of urolithiasis among NAFLD patients, although prospective cohort studies are still needed in the future.