Evaluation of the GUYS, S.T.O.N.E., and S-ReSC Scores in Predicting the Outcomes of Mini-Percutaneous Nephrolithotomy: A Prospective Study

Objectives Outcomes after percutaneous nephrolithotomy (PCNL) depend on various stone-related factors that have been combined into auxiliary nephrolithometric scoring systems (NSS). Few studies have evaluated these systems in mini-percutaneous nephrolithotomy (mini-PCNL). We undertook this study to evaluate Guy's stone score (GSS), the S.T.O.N.E. score, and the Seoul National University Renal Stone Complexity (S-ReSC) score for predicting stone-free status (SFS) and complications after mini-PCNL. Methods Data of patients aged 18 years and older who underwent mini-PCNL between July 2022 and June 2024 for renal stones >10 mm in largest diameter were analyzed. The clinical, perioperative, and radiological characteristics of the patients were recorded. The GSS, S.T.O.N.E., and S-ReSC scores were calculated and compared with the SFS, complications, and perioperative findings. The complete absence of stones on postoperative imaging confirmed the success of mini-PCNL. The modified Clavien-Dindo classification system was used to classify complications. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of the scores. Results A total of 410 patients were included in this study. SFS was achieved in 84.4% of the cases, and complications occurred in 10.7%. All three NSSs demonstrated a statistically significant association with SFS and complications. The AUC values of the GSS, S.T.O.N.E., and S-ReSC scores for predicting SFS were 0.7172, 0.7212, and 0.7174, respectively. The predictive power for complications was inferior to that for SFS, with AUCs of 0.6112, 0.6113, and 0.6259, respectively. Conclusion All scores showed good predictive ability for SFS and, to a lesser extent, for complications after mini-PCNL. None of the scores outperformed other scores.