Prognosis of chronic kidney disease with normal-range proteinuria: The CKD-ROUTE study

BACKGROUND: Although lower estimated glomerular filtration rate (eGFR) and higher proteinuria are high risks for mortality and kidney outcomes, the prognosis of chronic kidney disease (CKD) in patients with normal-range proteinuria remains unclear. METHODS: In this prospective cohort study, 1138 newly visiting stage G2–G5 CKD patients were stratified into normal-range and abnormal-range proteinuria groups. Study endpoints were CKD progression (>50% eGFR loss or initiation of dialysis), cardiovascular events, and all-cause death. RESULTS: In total, 927 patients who were followed for >6 months were included in the analysis. The mean age was 67 years, and 70.2% were male. During a median follow-up of 35 months, CKD progression, cardiovascular events, and mortality were observed in 223, 110, and 55 patients, respectively. Patients with normal-range proteinuria had a significantly lower risk for CKD progression (hazard ratio, 0.20; 95% confidence interval, 0.10–0.38) than those with abnormal-proteinuria by multivariate Cox proportional hazard analysis. We also analyzed patients with normal-range proteinuria (n = 351). Nephrosclerosis was the most frequent cause of CKD among all patients with normal-range proteinuria (59.7%). During a median follow-up of 36 months, CKD progression, cardiovascular events, and mortality were observed in 10, 28, and 18 patients, respectively. The Kaplan–Meyer analysis demonstrated that the risks of CKD progression and cardiovascular events were not significantly different among CKD stages, whereas the risk of death was significantly higher in patients with advanced-stage CKD. Multivariate Cox proportional hazard analysis showed that the risk of three endpoints did not significantly differ among CKD stages. CONCLUSION: Newly visiting CKD patients with normal-range proteinuria, who tend to be overlooked during health checkups did not exhibit a decrease in kidney function even in advanced CKD stages under specialized nephrology care.