T.O.HO.-PCNL Score for Predicting Success of Percutaneous Nephrolithotripsy: A New Score Development Study

<b>Background/Objectives:</b> The aim of this study was to develop a modified version of the T.O.HO. score for predicting percutaneous nephrolithotomy (PCNL) success. <b>Materials and Methods:</b> Patient demographics, stone-related parameters, perioperative findings, and postoperative outcomes were recorded. We reviewed the data of 155 patients who underwent percutaneous nephrolithotomy (PCNL) between October 2020 and December 2024. Patients were divided into two groups: success and failure. While preserving the validated components of the existing T.O.HO. score, the stone location parameter was restructured to more accurately reflect the anatomic challenges inherent to PCNL and was scored to include locations in the renal pelvis, upper, middle, lower and multiple calyces. The performance of the T.O.HO.-PCNL score in predicting surgical success was evaluated using ROC curve analysis. <b>Results:</b> The overall success rate was 65.8%. Patients in the successful group had smaller stone sizes and shorter operative times and hospital stays (<i>p</i> < 0.01). Preoperative hydronephrosis was more commonly observed among unsuccessful group (<i>p</i> < 0.05). The T.O.HO.-PCNL score was significantly lower in the successful group compared with the unsuccessful group. (<i>p</i> < 0.05). In the multivariate logistic regression analysis, stone size emerged as an independent predictor of PCNL success (OR: 1.076; 95% CI: 1.032-1.122; <i>p</i> < 0.001). ROC curve analysis demonstrated that the T.O.HO.-PCNL score had predictive value for PCNL success, with an optimal cut-off of 8.5 (AUC: 0.598; 95% CI: 0.506-0.690; <i>p</i> = 0.046). <b>Conclusions:</b> The T.O.HO.-PCNL scoring system is a promising nomogram for predicting stone-free status after PCNL in preoperative evaluation.