Validation of the Kidney Failure Risk Equation in Manitoba.

backgroundPatients with chronic kidney disease (CKD) are at risk to progress to kidney failure. We previously developed the Kidney Failure Risk Equation (KFRE) to predict progression to kidney failure in patients referred to nephrologists.

objectiveThe objective of this study was to determine the ability of the KFRE to discriminate which patients will progress to kidney failure in an unreferred population.

designA retrospective cohort study was conducted using administrative databases.

settingThis study took place in Manitoba, Canada. MEASUREMENTS: Age, sex, estimated glomerular filtration rate (eGFR), and urine albumin-to-creatinine ratio (ACR) were measured.

methodsWe included patients from the Diagnostic Services of Manitoba database with an eGFR <60 mL/min/1.73 m

resultsOf 1512 included patients, 151 developed kidney failure over the 5-year follow-up period. The 4-variable KFRE showed a superior prognostic discrimination compared with eGFR alone (area under the receiver operating characteristic curve [AUROC] values, 0.90 [95% confidence interval {CI}: 0.88-0.92] for KFRE vs 0.78 [95% CI: 0.74-0.83] for eGFR). At a 3% threshold over 5 years, the KFRE had a sensitivity of 97% and a specificity of 62%. At 10% risk, sensitivity was 86%, and specificity was 80%. LIMITATIONS: Only 11.7% of stage 3-5 CKD patients had simultaneous ACR measurement. The KFRE does not account for other indications for referral such as suspected glomerulonephritis, polycystic kidney disease, and recurrent stone disease.

conclusionsThe KFRE has been validated in a population with a demographic and referral profile heretofore untested and performs well at predicting 5-year risk of kidney failure in a population-based sample of Manitobans with CKD stages 3 to 5. Thresholds of 3% and 10% over 5 years are sensitive, specific, and can be used in clinical decision making. Further testing of the 4-variable KFRE and these thresholds in clinical practice should be considered.