Validation of the kidney failure risk equation in a Portuguese cohort

Introduction: In chronic kidney disease (CKD) patients, the risk of kidney replacement therapy (KRT) is highly variable. In 2011, Tangri et al. developed the kidney failure risk equations (KFRE) to predict the 2 and 5-year probability of requiring kidney replacement therapy (KRT). The KFRE is an easily calculated 4-variable equation which has been extensively validated in multiple cohorts. The aim of this study was to validate this risk score in a Portuguese cohort. Methods: We conducted a retrospective analysis of CKD patients stage 3–5 referred for nephrology consult at Centro Hospitalar Universitário Lisboa Norte during the first 6 months of 2018. Age, gender, estimated glomerular filtration rate (eGFR) and albuminuria were assessed. The 4-variable kidney failure risk equation (KFRE) calibrated to a non-North American population was calculated. Requirement of KRT was assessed in a 2-year follow-up. We assessed the Cox logistic regression method of the KFRE to predict KRT requirement and the discriminatory ability was determined using the receiver operating characteristic (ROC) curve. A cut-off value was defined as that with the highest validity. Results: 360 patients were included and 54.4% were male. Mean age was 74.9 ± 12.2 years, serum creatinine was 1.97 ± 0.84 mg/dL, eGFR was 33.4 ± 12.13 ml/min/1.73 m2 and albuminuria was 571.1 ± 848.3 mg/g. Mean calculated risk score was 6.2 ± 11.2%. Twenty-three patients required KRT (6.4%) in the two-year follow-up. The hazard ratio was 1.1 [95% CI (1.06–1.12), p 4.5% for 2-year nephrologist referral, with an hazard ratio of HR 26.7 [95% CI (6.15–116.3), p 4,5% para la derivación al nefrólogo de 2 años, con un índice de riesgo de HR 26,7 (IC del 95%: 6,15-116,3; p