Predicting success after retrograde intrarenal surgery for 10-20 mm renal stones: A comparison of scoring systems.

OBJECTIVE: To determine the predictive performance of the SMASH score in patients undergoing retrograde intrarenal surgery (RIRS) for single renal stones measuring 10-20 mm and to compare its predictive performance with commonly used scoring systems. METHODS: A total of 138 patients with a single renal stone measuring 10-20 mm who underwent RIRS were retrospectively analyzed. Residual stones smaller than 4 mm were considered clinically insignificant residual fragments (CIRFs). Patients who were stone-free or had CIRFs were considered to have achieved treatment success. Receiver operating characteristic (ROC) curve analysis was used to assess the discriminative performance of the R.I.R.S., S.T.O.N.E., T.O.HO., and SMASH scoring systems. The relationships between scoring systems, stone-free rate (SFR), and treatment success were evaluated. RESULTS: The SFR was 82.6%, increasing to 85.5% when CIRF cases were included. Median scores for the R.I.R.S., S.T.O.N.E. and T.O.HO. systems were 6, 10, and 6, respectively, whereas the mean SMASH score was 16.1. No significant differences were observed between stone-free and non-stone-free patients with respect to any of the evaluated scoring systems. ROC analysis demonstrated low discriminatory ability across all scoring systems for predicting stone-free status and treatment success. CONCLUSION: RIRS is an effective treatment option for patients with a single renal stone measuring 10-20 mm. In this patient population, none of the evaluated scoring systems, including the SMASH score, demonstrated adequate predictive performance for treatment success. Larger, multicenter, prospective studies are required to further clarify the role of the SMASH score in predicting RIRS outcomes.