Results
The mean age of the 656 patients who underwent RIRS was 46.1 ± 14.2 (16–88) years. 305 (52.5%) of the surgeries were performed for the left kidney and 276 (47.5%) of the surgeries were performed for the right kidney. While the mean stone burden was 169.5 ± 141 (16–1500) mm2, the mean stone density was 962.1 ± 327.2 (184–2240) HU. Preoperative clinical and demographic data of patients are shown in Table 1 .
The success rate of the RIRS was 73.3%. According to the multivariate logistic regression analysis, independent risk factors associated with failure were stone burden >200 mm2 (Odds Ratio (OR): 4.1; 95% Confidence lnterval (CI): 1.8–9.2; p: 0.001), the location of the stone in the lower pole (OR: 2.1; 95% Cl: 1.3–3.9; p: 0.013), surgical duration >60 minutes (OR: 1.9; 95% Cl: 1.2–3.2; p: 0.007), high modified S-ReCS (OR: 15.2; 95% Cl: 4.9–46.6; p <0.001) and high R.I.R.S score (OR: 7.2; 95% Cl: 1.6–31.5; p: 0.009) (Table 2).
The mean surgical duration was 54.3 ± 18.3 (20–120) min, and the patients were hospitalised for a mean period of 1.8 ± 3.9 (1–75) days postoperatively. While intraoperative complications were observed in 30.3% of the patients, postoperative complications occurred in 27.2% of them. Perioperative and postoperative data of the patients are shown in Table 3 .
Infective complications were detected in 47 (8.1%) patients who underwent RIRS. A total of 27 (4.6%) had only fever, 15 (2.5%) had urinary infection, 2 (0.3%) had sepsis and 3 (0.5%) had septic shock. According to the urinary culture results of 20 patients with postoperative urinary tract infection, sepsis and septic shock, 8 (40%) had Escherichia coli , 5 (25%) Pseudomonas aeoruginosa and 4 (20%) Enterococcus faecalis . Candida glabrata ,Candida dubliniensis and Klebsiellapneumoniae growths were detected each in one patient, each (5% per patient). According to the multivariate logistic regression analysis, the independent risk factors for the development of infective complications were found to be patients aged >50 years (OR: 1.8; 95% CI: 1–3.4; p: 0.049), surgical duration of >60 minutes (OR: 1.9; 95% Cl: 1.1–3.5; p: 0.027) and a high R.I.R.S score (OR: 8.9; 95% CI: 1.9–42.4; p: 0.006) (Table 4) .
ROC curves were used to evaluate the effectiveness of the scoring systems in predicting infective complications in the RIRS procedure(Figure 1) . ROC curve analysis showed that the R.I.R.S scoring system can be used as a marker to predict infective complications. (Area under the curve (AUC): 0.619, CI: 0.55–0.69; p: 0.007) The cut-off point for the R.I.R.S scoring system was found to be 5.5 points using Youden’s test. When patients with kidney stones who scored above this score in the preoperative period were grouped as ‘patients with infective complications’, the sensitivity of this scoring system was found to be 0.894, and its specificity was 0.35. RUTS and modified S-ReCS were far from predicting infective complications. (AUC: 0.515, CI: 0.429–0.601; p: 0.73 and AUC: 0.542, CI: 0.457–0.626; p: 0.345, respectively) (Table 5) .