Planning of kidney replacement therapy in advanced CKD using the KFRE formula in a Spanish multicenter cohort

The Kidney Failure Risk Equation (KFRE) is widely used to estimate the risk of kidney replacement therapy (KRT), but evidence in real-world multicenter advanced chronic kidney disease (ACKD) cohorts-particularly among older patients with substantial competing mortality-remains limited.

We conducted a multicenter retrospective cohort study including adults with ACKD [baseline estimated glomerular filtration rate (eGFR) <20 ml/min/1.73 m²] followed at specialized multidisciplinary clinics in Barcelona and Seville (2017-2022). The 2-year 4-variable KFRE (age, sex, eGFR, and urine albumin-to-creatinine ratio) was externally validated for predicting KRT initiation, treating death as a competing event. Discrimination was assessed using time-dependent area under the curve (AUC); calibration was evaluated using decile-based plots and quantitative metrics [calibration-in-the-large (CITL) and Brier score] using Fine-Gray competing risk methods. Clinical utility was explored using decision curve analysis (DCA) and a 20% KFRE threshold in patients aged ≥65 years.

A total of 503 patients were included. During follow-up, 248 patients initiated KRT and 94 died before KRT. The 2-year 4-variable KFRE showed good discrimination [time-dependent AUC 0.82, 95% confidence interval (CI) 0.73-0.91], preserved across age strata. Calibration demonstrated appropriate risk ordering across deciles with mild underestimation (CITL -0.21 by Fine-Gray; Brier score 0.23). In patients aged ≥65 years, a KFRE ≥20% was strongly associated with KRT initiation in competing risk models (subdistribution hazard ratio 5.92, 95% CI: 4.08-8.60). DCA showed positive net benefit across clinically relevant thresholds.

In a multicenter Spanish ACKD cohort, the 2-year KFRE demonstrated robust discrimination and acceptable calibration. These findings highlight the clinical utility of the KFRE for risk stratification and KRT planning in older patients with ACKD.