The combined contribution of albuminuria and glomerular filtration rate to the prediction of cardiovascular mortality in elderly men

Background. Cardiovascular risk prediction is particularly important in the primary prevention of cardiovascular disease (CVD). Yet, data on whether the combined addition of albuminuria and estimated glomerular filtration rate (eGFR) improves cardiovascular risk prediction in individuals without CVD in the community is scarce. Methods. We investigated associations between urinary albumin excretion rate (UAER), cystatin C-based eGFR and cardiovascular mortality in a community-based cohort of elderly men (ULSAM study; n = 1113, mean age 71 years, 208 cardiovascular deaths, median follow-up 12.9 years) with prespecified analyses in participants without CVD (n = 649, 86 cardiovascular deaths). Results. Using multivariable Cox regression, higher UAER and lower eGFR were associated with increased risk for cardiovascular mortality independently of established cardiovascular risk factors in the whole sample and in men without CVD at baseline [subsample without CVD: UAER; hazard ratio (HR) per 1 SD 1.26, 95% confidence interval (CI) 1.05-1.51, P = 0.01; eGFR: HR per 1 SD 0.74, 95% CI 0.59-0.92, P = 0.007]. Analyses of model discrimination, calibration, reclassification and global fit suggested that UAER and eGFR also add relevant prognostic information beyond established cardiovascular risk factors in participants without prevalent CVD. Interestingly, established cutoffs used to diagnose microalbuminuria (UAER > 20 mu g/min) and chronic kidney disease Stage 3 (eGFR < 60 mL/min/1.73m(2)), appeared less suitable for cardiovascular risk prediction [integrated discrimination improvement (IDI) 0.006, P = 0.11], while cutoffs UAER > 6 mu g/min and eGFR < 45 mL/min/1.73m(2) significantly improved IDI (0.047, P < 0.001). Conclusions. UAER and eGFR improved cardiovascular risk prediction beyond established cardiovascular risk factors, suggesting that these kidney biomarkers may be useful in predicting cardiovascular death in elderly men.