Covered Metal Ureteral Stents in the Maintenance Treatment of Refractory Ureteral Stricture: A Prospective, Multi-Center, and Large-Scale Cohort Study with 3-Year Outcomes

<b><i>Introduction:</i></b> Covered metal ureteral stents (CMUSs) have shown promising results for ureteral stricture. However, 3-year outcomes of CMUSs are lacking. This study aimed to evaluate the 3-year efficacy and safety of CMUSs in the maintenance treatment of refractory ureteral stricture (RUS) and explore risk factors for CMUSs-related complications. <b><i>Methods:</i></b> Between August 2018 and July 2021, 321 patients (366 renal ureter units [RUUs]) with RUS who underwent CMUSs implantation surgery were prospectively recruited in this study. A regular 3-year follow-up protocol including serum biochemistry test, abdominal imaging, and ureteral stent syndrome questionnaire was established to analyze ureteral patency and patient's quality of life (QoL). The primary ureteral patency was defined as patent ureters without CMUSs-related complications, while secondary ureteral patency also included those that restored patent after endoscopic interventions. <b><i>Results:</i></b> The study included 105 (32.7%) patients with stone-related benign ureteral stricture (BUS), 90 (28.0%) with nonstone-related BUS, 76 (23.7%) with radiation-induced ureteral stricture (RIUS), and 50 (15.6%) with malignant ureteral stricture. There existed significant differences in mean serum creatinine levels and renal pelvis widths before and after CMUSs implantation (all <i>p</i> < 0.001). Patients' QoL significantly improved at postoperative 12 and 36 months (both <i>p</i> < 0.001). CMUSs-related complications occurred in 95 (26.0%) RUUs, including 24 (6.6%) with end-stent ureteral restenosis, 28 (7.7%) with stent migration, 31 (8.5%) with stent encrustation, 7 (1.9%) with infection, and 5 (1.4%) with ureteral fistula. The 3-year primary and secondary ureteral patency rate was 74.0% and 90.4%, respectively. However, among patients with RIUS, the primary and secondary ureteral patency rates were only 54.7% and 77.4%, respectively. <b><i>Conclusion:</i></b> CMUSs are effective and safe in the 3-year maintenance treatment of RUS. Patients with CMUSs experience long-term improved QoL. However, patients who underwent radiotherapy are susceptible to developing CMUSs-related complications.