Results
There were 56 patients in Group 1 and 95 patients in Group 2. The demographic characteristics of the patients and the stone-related variables were similar between the groups. The preoperative serum creatinine level, the rate of preoperative double J stenting and the rate of hydronephrosis were also similar between the groups. The mean number of ESWL sessions and the mean duration between the last ESWL session and RIRS in Group 1 were 2.9 ± 1.0 times and 68.4 ± 69.9 days, respectively (Table 1).
The stone-free rates of Group 1 and Group 2 were 94.6% and 93.7%, respectively (p = .893). The mean operation time was 63.3 ± 24.5 min for Group 1 and 63.4 ± 25.6 min for Group 2 (p = .997). The fluoroscopy screening time and hospitalization time were significantly higher in the Group 1 patients. Peroperative and postoperative complications were similar between the groups (Table 2). All of the peroperative complications in both groups were classified as Grade 1 on the Clavien-Dindo classification scale, which included mucosal erosion and mild bleeding. A total of 7 (12.5%) patients in Group 1 had postoperative complications, including postoperative fever that required antibiotherapy. Among the patients in Group 2, 10 (10.5%) had postoperative complications, including fever (8 patients) and urosepsis (2 patients).
In order to evaluate the possible predictive effect of ESWL on the efficacy and safety of RIRS for proximal ureter stone treatment, a model of variables composed of age, sex, number of ESWL sessions, the duration between ESWL and RIRS, stone density, presence of hydronephrosis and stone volume was formed. According to this group analysis, the duration between ESWL and RIRS (in weeks) was found to be a predictive factor for stone-free status. On the other hand, the AUC (0.662) was found to be statistically non-significant (p = .126) and the Youden index was low (0.400); hence, it was suggested that the time from ESWL to RIRS had no discriminatory ability. Nonetheless, all patients who underwent RIRS after duration of 10 weeks post-ESWL were stone-free, and the cut-off duration of 10 weeks from ESWL to RIRS had reasonable/favourable discriminating ability with 51% sensitivity and 88% specificity. The OR for the duration between ESWL and RIRS was 1.27 (95% CI: 1.11-1.44) for each week. The relation between the model variables and the operation time, hospitalization time and complications are given in Table 3.