Albuminuria independently predicts cardiovascular and all-cause mortality in a middle-aged and elderly Chinese population

Aim. To investigate the relationship between albuminuria and mortality in a middle-aged-to-elderly Chinese population. Methods. A total of 2,344 individuals aged over 40 in the same district were interviewed and followed up for 4 years. Information on survival or cause of death was recorded. A total of 2,181 participants with detailed information were finally recruited. Baseline overnight urine samples were obtained to measure urinary albumin and creatinine. The urinary albumin excretion rate was expressed as albumin-to-creatinine ratio (ACR). Participants were divided into three groups, according to their ACR: normoalbuminuria (ACR < 30 mg/g), microalbuminuria (>= 30 - <300 mg/g ACR) and macroalbuminuria (ACR < 300 mg/g). The Cox proportional hazard model was used to analyze the relationships between albuminuria and cardiovascular and all-cause mortalities. Results. Seventy-seven deaths with known causes were registered. The prevalences of microalbuminuria and macroalbuminuria at baseline were 8.3% and 1.6%, respectively. Cardiovascular mortalities in the normoalbuminuria, microalbuminuria and macroalbuminuria groups were 2.4, 11.0, and 36.8/1,000 person years (pyrs) respectively, and all-cause mortalities were 6.9, 20.6, and 58.8/1,000 pyrs. After adjusting for confounding factors, the relative risks (RR) of cardiovascular mortality were 2.72 (95% CI, 1.06-4.20) in the microalbuminuria group, and 4.87 (95% CI, 2.46-9.45) in the macroalbuminuria group. Adjusted RRs for all-cause mortality were 2.01 (95% CI, 0.96-4.77) and 3.76 (95% CI, 1.52-7.15) in the two groups, respectively. Conclusion. Albuminuria is a useful predictor of cardiovascular mortality and all-cause mortality in the general population.