Comparison of Scoring Systems in Predicting Stone Free Rate (SFR) in Patients with Fluoroless Retrograde Intrarenal Surgery (fRIRS)

Abstract: Between March 2022 and October 2023, a prospective study evaluated 216 patients who underwent Fluoroless Retrograde Intrarenal Surgery (fRIRS), including right, left, and bilateral procedures. The study compared the predictive abilities of Guy’s Stone Score (GSS), Seoul National University Renal Stone Complexity Score (S-ReSC), and Resorlu-Unsal Stone Score (RUSS) for stone-free rate (SFR). The patient cohort consisted of 164 men (76.3%) and 52 women (23.7%), with an average age of 57.3 years. The distribution of procedures was 49.07% right fRIRS, 49.5% left fRIRS, and 1.43% bilateral fRIRS. GSS scores were evenly split, with 50% of patients in Grade I and 50% in Grade II. S-ReSC scores were predominantly high (65.3%), with 20.4% moderate and 14.4% low. RUSS scores were distributed as 1 (43 patients), 2 (112 patients), and 3 (61 patients). The overall SFR was 82.1%, indicating a high success rate in eliminating residual stones post-procedure. In conclusion, GSS was the most accurate scoring system for predicting SFR, with an AUC of 75%, compared to S-ReSC (72%) and RUSS (70%). All three scoring systems demonstrated good predictive ability, with AUC values ≥70%. Fluoroless RIRS, a minimally invasive surgical option for kidney stones, has gained popularity due to technological advancements. While GSS showed the highest accuracy, the study highlighted the utility of all three scoring systems in preoperative planning and outcome prediction. These findings underscore the importance of scoring systems in optimizing surgical management and improving patient outcomes in kidney stone treatment. Keywords: stone free rate; retrograde intrarenal surgery; Resorlu-Unsal score; Guy’stone score; Seoul nation university renal stone complexity score