Objective To explore the risk factors related to the therapeutic effects after flexible ureteroscopic lithotripsy (FURL), and construct a new scoring model to predict the stone clearance rate (SFR) after FURL.

Methods A retrospective analysis was conducted on the clinical data of upper urinary tract calculi patients with treated with FURL, and the SFR after the first stage of surgery was simultaneously calculated. The independent predictors were obtained through single-factor analysis and multiple logistic regression analysis. A nomogram was drawn and scores were assigned to each parameter based on the weights of the relevant parameters in the nomogram, thereby a new scoring model was constructed. The predictive performance between scoring model and STONE score was compared using the receiver operating characteristic curve (ROC).

Results A total of 247 patients were included in this study, among which 157 cases (63.6%) were in the stone clearance group and 90 cases (36.4%) were in the stone residue group. The results of univariate analysis showed that the number of stones, long diameter of stones, area of stones, density of stones and position of stones all had an impact on the SFR after FURL surgery (P ＜ 0.01). The results of multivariate logistic regression analysis showed that the stone area, stone density and stone location were independent predictors of SFR after FURL (P ＜ 0.05 to P ＜ 0.01). Based on this, a nomogram with an AUC of 0.808 and a new scoring model were established. The AUC of the new scoring model was 0.775, while that of the STONE score was 0.640.

Conclusions The stone area, stone density and stone location are the factors affecting the therapeutic effect after FURL. The new scoring model constructed based on the above three indicators can be used as an effective means for evaluating SFR after FURL and can provide a reference for clinical decision-making.