Association of obesity-related indices with rapid kidney function decline and chronic kidney disease, a study from a large longitudinal cohort in China

Introduction: Obesity has been established as a significant risk factor for rapid kidney function decline (RKFD) and chronic kidney disease (CKD). However, the comparative prognostic value of various obesity-related indices in predicting RKFD and CKD remains inadequately elucidated. The objective of this study was to explore the correlations between ten obesity-related indices: body mass index (BMI), Chinese visceral adiposity index (CVAI), waist-to-height ratio (WHtR), visceral adiposity index (VAI), body roundness index (BRI), a body shape index (ABSI), lipid accumulation product (LAP), waist triglyceride index (WTI), relative fat mass (RFM), and conicity index (C-index), and RKFD and CKD. Methods: This retrospective longitudinal cohort study leveraged data sourced from the China Health and Retirement Longitudinal Study (CHARLS). Multivariate logistic regression models with covariate adjustment were employed to assess independent associations between obesity-related indices and clinical outcomes. Restricted cubic spline (RCS) regression analyses were performed to characterize potential nonlinear relationships. Predictive performance was quantified through receiver operating characteristic (ROC) curve analysis, with area under the curve (AUC) comparisons. Results: A total of 1,620 participants were enrolled in this study. Among them, 109 participants developed RKFD, and 60 progressed to CKD. Adjusted logistic regression revealed significant positive associations between CVAI, VAI, LAP, WTI and RKFD risk, while BRI and C-index demonstrated per standard deviation (SD) increases associated with CKD progression. RCS curve analysis demonstrated that CVAI and LAP exhibited a nonlinear relationship with the risk of RKFD, while VAI and WTI had a linear relationship. Moreover, the C-index had a nonlinear relationship with the risk of CKD, whereas BRI had a linear relationship. ROC analysis revealed WTI as the superior RKFD predictor and ABSI as the optimal CKD progression indicator among the evaluated obesity-related indices. Conclusion: This study comprehensively investigated the associations between ten obesity-related indices and both RKFD and CKD. Our findings indicated that CVAI, VAI, LAP, and WTI were associated with RKFD, with WTI exhibiting the highest predictive value. Furthermore, BRI and C-index were associated with CKD, with ABSI demonstrating the highest predictive value for the progression to CKD.