Reduced Kidney Function, Albuminuria, and Risks for All-cause and Cardiovascular Mortality in China: A Population-based Cohort Study

BACKGROUND Previous studies have indicated that reduced kidney function and albuminuria are associated with increased risk of mortality and adverse cardiovascular outcomes, however, the evidence from the Asian population is limited. We investigated the association between the indicators of chronic kidney disease (CKD) and all-cause mortality, as well as cardiovascular mortality among a general population in China. METHODS We conducted an observational study among 47,204 Chinese adults, from a cross-sectional survey, whose survival status is identified through December 31, 2013. Estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR) were used as indicators of CKD. We determined the rates of all-cause and cardiovascular mortality. RESULTS The incidence rates for both all-cause and cardiovascular mortality increased with the advanced stages of reduced eGFR or elevated ACR. Elevated ACR levels were found to be significantly associated with increased risk of both all-cause and cardiovascular mortality, as shown in the Cox proportional hazards regression model. The multivariable adjusted hazard ratios (HR) associated with all-cause mortality were 1.26 (95% confidence interval [CI]: 1.04-1.53) for those with ACR 30-299 mg/g and 2.07 (95% CI: 1.40-3.04) with ACR ≥ 300 mg/g, compared to those with ACR <30 mg/g. The corresponding HRs for the above ACR levels associated with cardiovascular mortality were 1.08 (95% CI: 0.77-1.50) and 2.32 (95% CI: 1.31-4.12), respectively. We did not identify reduced eGFR as a risk predictor in the multivariable adjusted model for the adverse outcomes in the population, however, an interaction between eGFR and age were detected. Stratified analyses revealed that the associations of reduced eGFR (<60 mL/min/1.73 m2) with all-cause mortality were prominent among participants aged less than 65 years. CONCLUSIONS Albuminuria was associated with an elevated risk of all-cause and cardiovascular mortality among the Chinese population, however, the association of reduced kidney function with all-cause mortality was not clear.