Proteinuria predicts mortality in kidney patients

Proteinuria is a useful predictor of outcomes in patients with chronic kidney disease, a new study found.

The Canadian cohort study included more than 900,000 adults who had at least one outpatient serum creatinine measurement and did not require dialysis at baseline. Data were gathered in a 2002-2007 registry that included estimated glomerular filtration rates (eGFRs) and proteinuria measurements. The study was published in the Feb. 3 Journal of the American Medical Association.

Over the median follow-up of 35 months, 3% of the patients died. Although mortality rates were higher overall in patients with lower eGFRs, adjusted mortality rates were more than twice as high in patients with heavy proteinuria and eGFR of at least 60 mL/min/1.73 m² compared to patients with normal protein excretion and eGFR of 45 to 59.9 mL/min/1.73 m². Similar results were observed whether proteinuria was measured by urine dipstick or albumin-creatinine ratio. The study also found similar trends for the outcomes of hospitalization with acute myocardial infarction, end-stage renal disease and doubling of serum creatinine level.

Based on the results, it appears that patients with heavy proteinuria and normal eGFR have worse outcomes than those with moderately reduced eGFR and no proteinuria, the study authors concluded. Although current guidelines call for staging chronic kidney disease (CKD) based on eGFR, they should perhaps be revised, given that use of that measurement alone may miss clinically relevant gradients in risk. The authors also suggested that consideration be given to subdividing CKD stage 3, since their study found significant heterogeneity of risk among this population.