Association of Liver Fibrosis Markers with Mortality Outcomes in Patients with Chronic Kidney Disease and Coronary Artery Disease: Insights from the NHANES 1999-2018 Data

Introduction: The objective of this research is to explore the possible link between markers of liver fibrosis and survival rates in a group of adults who have been diagnosed with both chronic kidney disease (CKD) and coronary artery disease (CAD). Methods: The National Health and Nutrition Examination Survey (NHANES) data (1999-2018) for participants with both CAD and CKD were analyzed. The Fibrosis-4 Index (FIB-4), Nonalcoholic Fatty Liver Score (NFS), Forns index and Aspartate Aminotransferase/Alanine Aminotransferase (AST/ALT) ratio were identified as crucial biomarkers. All-cause and cardiovascular disease (CVD) mortality were primary outcomes, assessed using Cox models, Kaplan-Meier curves, and ROC analysis. Results: A total of 1,192 CKD and CAD patients were included. The Cox regression analysis revealed substantial correlations between elevated FIB-4, NFS, Forns index and AST/ALT levels and a heightened risk of all-cause (HR 1.188, 95%CI 1.108-1.274; HR 1.145, 95%CI 1.069-1.227; HR 1.142, 95%CI 1.081-1.201; HR 1.316, 95%CI 1.056-1.639, respectively) and CVD mortality (HR 1.133, 95%CI 1.007-1.275; HR 1.155, 95%CI 1.024-1.303; HR 1.208, 95%CI 1.109-1.316 and HR 1.636, 95%CI 1.203-2.224, respectively). The ROC analysis indicated comparable predictive accuracy for all three biomarkers, with AST/ALT showing slightly superior performance. Conclusion: Liver fibrosis markers, including AST/ALT, NFS, Forns index and FIB-4, are significant mortality predictors in CAD-CKD patients. The AST/ALT ratio, being easily measurable, may serve as an effective predictive tool for risk stratification in this population.