Background: Longitudinal studies of the mortality and renal outcomes among the population with an estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m(2) and among the elderly are limited, especially in developing countries.
Methods: This prospective cohort study included 1563 residents aged 59.5 ± 9.4 years from an urban district of Beijing, China. All participants had an eGFR >30 mL/min/1.73 m(2). Urinary albumin-to-creatinine ratio and eGFR were assessed at baseline, and their relation with mortality and renal function decline after a 4-year follow-up were analyzed.
Results: During 4 years (6142 person-years) of follow-up, 59 deaths occurred (9.6 per 1000 person-years). After adjusting for potential confounders, albuminuria was associated with increased risk of mortality, with an odds ratio (OR) of 3.09 [95% confidence interval (CI) 1.53-6.26]. Altogether 183 patients (12.3%) developed renal function decline, with a median change of eGFR of -20.0 mL/min/1.73 m(2). Presence of albuminuria was significantly associated renal function decline, with an OR of 1.79 (95% CI 1.02-3.15). Plasma uric acid (OR = 1.25/59 μmol/L increase, 95% CI 1.10-1.43) and age (OR = 1.35/5 years increase, 95% CI 1.22-1.50) was also independently associated with renal function decline. Baseline eGFR was not significantly associated with either mortality or renal function decline in our analysis.
Conclusions: Compared with eGFR, albuminuria is a strong independent predictor for both mortality and renal function decline among a Chinese population with normal or mildly impaired renal function. Furthermore, plasma uric acid level and age are also independently associated with renal function decline and therefore may be used for identifying patients at higher risk of chronic kidney disease progression.