External validation of the nomograms for predicting renal function at 1 year after partial nephrectomy with only preoperative factors

Nephron-sparing surgery has been widely used as treatment for small renal tumors if technically feasible. Compared with radical nephrectomy, partial nephrectomy confers less development of chronic kidney disease. Nevertheless, partial nephrectomy causes certain renal damage. Predictive tools of functional outcomes after partial nephrectomy are quickly developing. In our retrospective study, we assessed the accuracy and generalizability of two reported nomograms for predicting renal function at one year after partial nephrectomy with only preoperative factors. Our cohort consisted of a total of 107 patients. We calculated the preoperative and 1-year postoperative estimated glomerular filtration rate by modification of diet in renal disease and chronic kidney disease epidemiology collaboration formulas in patients undergoing partial nephrectomy. We applied the nomograms to each patient to the, calculated the adjusted coefficient of determination and analyzed the accuracy of the models, and the sensitivity and specificity to estimate postoperative chronic kidney disease. With modification of diet in renal disease and chronic kidney disease epidemiology collaboration formulas, the adjusted coefficients of determination were 0.75 and 0.62. The accuracies were 90.7% and 87.4%, the sensitivities to estimate postoperative chronic kidney disease were 50.0% and 30.8%, and the specificities were 95.0% and 97.6%, respectively. This external validation study showed that the nomograms for predicting renal function at one year after partial nephrectomy with only preoperative factors were applicable to a Taiwanese population. The nomograms have high accuracy and seem helpful in counseling and decision making before partial nephrectomy.