External Validation of Toulouse-Rangueil eGFR12 Prediction Model After Living Donor Nephrectomy

Decreased postdonation eGFR is associated with a higher risk of ESRD after living kidney donation, even when accounting for predonation characteristics. The Toulouse-Rangueil model (TRM) estimates 12 month postdonation eGFR (eGFR12) to inform counseling of candidates for living donation. The TRM was validated in several single-center European cohorts but has not been validated in US donors. We assessed the TRM in living kidney donors in the US using SRTR data 1/2000–6/2021. We compared the 2021 CKD-EPI equation eGFR12 observed estimates to the TRM eGFR12 predictions. Median (IQR) bias was −3.4 (−9.3, 3.4) mL/min/1.73 m(2). Bias was higher for males vs. females (bias [IQR] −4.4 [−9.9, 1.8] vs. −2.9 [−8.8, 4.1]) and younger (31–40) vs. older donors (>50) (bias −4.9 [−10.6, 3.0] vs. −2.1 [−7.5, 4.0]). Bias was also larger for Black vs. White donors (bias (−6.7 [−12.1, −0.3], p < 0.001) vs. (−3.4 [−9.1, 3.1], p < 0.001)). Overall correlation was 0.71. In a sensitivity analysis using the 2009 CKD-EPI equation, results were generally consistent with exception to a higher overall bias (bias −4.2 [−9.8, 2.4]). The TRM overestimates postdonation renal function among US donors. Overestimation was greatest for those at higher risk for postdonation ESRD including male, Black, and younger donors. A new equation is needed to estimate postdonation renal function.