Objective: To evaluate predictive capability and clinical applicability of the current nephrolithometric scoring systems of S.T.O.N.E. score, Guy's scoring system (GSS), CROES (Clinical Research Office of the Endourological Society) nomogram, and S-ReSC (Seoul National University Renal Stone Complexity) score for percutaneous nephrolithotomy (PCNL) outcomes in the same cohort in a prospective study. Methods: Consecutive patients undergoing PCNL between 2015 and 2018 were included calculating the four scores in the same cohort. Stone-free status (SFS), complications, operative time (OT), estimated blood loss (EBL), fluoroscopy time, and length of hospital stay were investigated. Receiver operator characteristic (ROC) curves for predictive accuracy and regression analysis for predictors of SFS were performed. Results: In all, 162 PCNLs were accomplished and analyzed. Overall, SFS was 75.9% and complication rate was 30.9%. The mean acquisition time of scores was 52.9 ± 0.5 seconds for GSS, 05.1 ± 0.3 seconds for S.T.O.N.E. score, 224 ± 3.1 seconds for CROES, and 102.6 ± 3.5 seconds for S-ReSC score. SFS had the best association with CROES grade. Clavien grade was associated with S.T.O.N.E. score. Moreover, EBL and OT had best association with S-ReSC score. All scores had comparable predictive accuracy on ROC curves regarding SFS. Stone essence and tract length are not different in cases with residual stones. Number of involved calyces, single vs multiple stones and renal pelvic obstruction were significant predictors of SFS in regression analysis. Conclusion: The four scoring systems had comparable predictive accuracy for SFS. However, S.T.O.N.E. and S-ReSC scores were easily applicable and provided better association with EBL and OT compared with the GSS score. Number of involved calyces, stone multiplicity, and renal pelvic obstruction were significant predictors of SFS; hence, further studies are needed to invent a universally agreeable scoring system covering reported shortcomings in the currently used scores.

Ashraf Abdel Aal

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