Cardiometabolic risk burden and kidney function in middle-aged and older adults: evidence from two national, cross-sectional studies in China and the United States.

Individual cardiometabolic risk factors (CMRFs) are contributors to reduced kidney function, their cumulative impact and population-specific differences remain unclear. This cross-sectional study investigated the association between incremental CMRFs and estimated glomerular filtration rate (eGFR). We analyzed data from two nationally representative surveys, China Health and Retirement Longitudinal Study wave 3 ( = 10,043) and the U.S. Health and Retirement Study wave 13 ( = 9,373), comprising 19,416 participants aged ≥45 years. Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, integrating serum creatinine and cystatin C, were applied to calculate eGFR, categorized into normal (≥90 mL/min/1.73 m), mildly decreased (60-89 mL/min/1.73 m), and moderately/severely decreased (<60 mL/min/1.73 m). Multinomial logistic regression was employed to assess the association between cumulative CMRFs (0-5) and eGFR categories, adjusting for covariables. Analyses were conducted on unweighted data without applying complex survey sampling weights. A graded association between the cumulative burden of CMRFs and eGFR decline was observed. Each additional CMRF was associated with an increased risk of mild eGFR decline in the fully adjusted model (relative risk ratio [RRR] = 1.141, 95% confidence interval [95% CI]: 1.108-1.175) and moderate/severe eGFR decline (RRR = 1.433, 95% CI: 1.364-1.505). Participants with five CMRFs had a significantly higher risk of moderate/severe eGFR decline compared to those without CMRFs (RRR = 6.178; 95% CI: 3.718-10.268). Predictive margins showed that eGFR decline was more prevalent in the American population compared to the Chinese population. These cross-sectional findings suggest that integrating routine screening and management of cardiometabolic risk factors into CKD prevention programs may help protect kidney health in aging populations.