Proteinuria and rate of change in kidney function in a community-based population

Abstract

Proteinuria identifies patients at risk for adverse clinical outcomes, but it is unclear whether proteinuria correlates with the rate of renal decline. We examined the association between proteinuria and rate of change in estimated GFR (eGFR) in a cohort of 638, 150 adults from a province-wide registry in Alberta, Canada, who had a measure of proteinuria and three or more outpatient serum creatinine measurements over a period of ≥1 year. An adjusted sex-specific linear mixed-effects model was used to determine the rate of change in eGFR per year for patientswith normal, mild, and heavy proteinuria, stratified by baseline kidney function (eGFR ≥90, 60-89. 9, 45-59. 9, 30-44. 9, and 15-29. 9 ml/min per 1. 73 m2). In men, heavy proteinuria and a baseline eGFR of 45-59. 9 ml/min per 1. 73m2 correlated with a change in eGFR of22. 16 (95% confidence interval [CI], 22. 37 to21. 95)ml/min per 1. 73m 2 per year, whereasmild proteinuria and a baseline eGFR of 30-44. 9ml/min per 1. 73m2 correlated with a change in eGFR of20. 51 (95%CI, 20. 70 to 20. 32) ml/min per 1. 73 m2 per year. Similar trends were observed for female, elderly, and diabetic patients. Notably, normal protein levels and a lower baseline eGFR (15-29. 9 ml/min per 1. 73 m2) correlated with stable or improved renal function. In conclusion, our results suggest that proteinuria of increasing severity is associatedwith a faster rate of renal decline, regardless of baseline eGFR, and the combined effect should be considered in patients with CKD. Copyright © 2013 by the American Society of Nephrology.