External validation of a proposed prognostic model for the prediction of 1-year postoperative eGFR after living donor nephrectomy.

PURPOSE: The goal of this study was to externally validate the recently proposed prognostic model for the prediction of estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 1 year after living donor nephrectomy.

METHODS: 130 living kidney donors (median age at donation 52.3 years, range 24.7-75.6 years) were investigated before and after donation between March 2000 and April 2016. Preoperative eGFR values varied between 61.7 and 148.4 ml/min (mean: 89, median: 88). Observed eGFR 1 year after transplantation (±45 days) ranged between 36.3 and 97.1 ml/min (mean: 55, median: 53). 70.8% of donors displayed eGFR values < 60 ml/min 1 year after donation. Predicted eGFR 1 year after donation was determined using the prognostic model proposed by Benoit et al. (Int Urol Nephrol 49(5):793-801. doi: 10.1007/s11255-017-1559-1 , 2017): postoperative eGFR ml/min/1.73 m2  = 31.71 + (0.521 × eGFR in ml/min prior to donation -0.314 × Age in years at donation). Pearson correlation and receiver operating characteristics curve (ROC-curve) were used to assess external validity of the proposed prognostic model to predict postoperative eGFR in ml/min and eGFR < 60 ml/min.

RESULTS: The correlation between predicted and observed eGFR 1 year after donation was significant (p < 0.001; R 2  = 0.594). The area under the ROC-curve (AUROC) demonstrated a high sensitivity and specificity for predicted eGFR values < 60 ml/min (AUROC = 0.866).

CONCLUSIONS: The proposed prognostic model for the prediction of postoperative eGFR was successfully validated in our cohort. We therefore consider the model as generally applicable.