External validation and comparison of current scoring systems in retrograde intrarenal surgery: Multi-institutional study with 949 patients.

All four scoring systems (RUSS, modified S-ReSC, Ito's nomogram, and R.I.R.S.) could predict stone-free status after f-URS, however, the AUC values are not satisfactory in our large patient cohort. Although these scoring systems were not developed for predicting post-operative complications, they were associated with complications in our study. However, these four scoring systems have some significant limitations. The ideal scoring system is yet to be developed.