A New Scoring System for Predicting Stone-free Rate After Retrograde Intrarenal Surgery: The “Resorlu-Unsal Stone Score”

ObjectiveTo investigate the prognostic factors associated with the treatment efficacy of retrograde intrarenal surgery (RIRS) and develop a scoring system for predicting the stone-free rate after this surgery.MethodsWe performed a retrospective analysis of 207 patients who underwent RIRS for renal stones between January 2009 and September 2011. Patient age, gender, body mass index, stone size, stone side, stone location, stone composition, number of stones, lower pole infundibulopelvic angle, using anticoagulant therapy, abnormal skeletal anatomy, and abnormal renal anatomy were investigated as potential preoperative predictive factors.ResultsThe present study included 111 (53.6%) men and 96 (46.4%) women. Mean patient age was 32.9 ± 18.8 years (range 1–74) and mean stone size was 16.2 ± 4.1 mm (range 8–40). Overall, 178 of the 207 (86%) patients were stone free after the initial treatment. Univariate analysis showed that stone size (P <.001), stone location (P = .025), stone composition (P = .01), stone number (P = .049), renal malformations (P = .042), and lower pole infundibulopelvic angle (P = .003) had significant influence on the stone-free rate after RIRS. Multivariate analysis excluded stone location from the logistic regression model, whereas other factors maintained their statistically significant effect on success rate, indicating that they were independent predictors.ConclusionOur study demonstrated that stone size, stone number, stone composition, infundibulopelvic angle, and renal malformations are significant predictors of RIRS outcome. A scoring system based on these factors helps separate patients into outcome groups and facilitates treatment planning.