Tip bendable suction ureteral access sheath versus traditional sheath in retrograde intrarenal stone surgery: an international multicentre, randomized, parallel group, superiority study.

Background: Retrograde intrarenal surgery (RIRS) is the main treatments for upper urinary tract stones. The Ureteral Access Sheath (UAS) serves as a supplementary tool, facilitating direct kidney access during RIRS. High quality of evidence comparing tip bendable suction ureteral access sheath (S-UAS) with traditional UAS in RIRS for the treatment of renal and ureteral stones is lacking. The purpose of the study is to compare the efficacy and safety of S-UAS with traditional UAS in RIRS for the treatment of renal or ureteral stones ≤30 mm. Methods: An international, multicenter, and superiority randomized controlled trial included 320 intention-to-treat patients across 8 medical centers in China, the Philippines, Malaysia and Turkey from August 2023 to February 2024. The inclusion criteria were patients ≥18 years old with renal or ureteral stones ≤30 mm. RIRS was performed using either S-UAS or traditional UAS. The primary outcome was the immediately stone-free rate (SFR). Secondary outcomes included SFR 3 months after operation, operating time, hospital stay, auxiliary procedures, complications (using the Clavien-Dindo grading system), and improvement in the Quality of Life (QoL) score. Differences between proportions [risk difference (RD)]/means [mean difference (MD)] and 95% confidence intervals (CI) were presented. This study is registered at ClinicalTrials.gov: NCT05952635. Findings: The S-UAS group demonstrated a significantly higher immediately SFR (81.3% versus 49.4%; RD 31.9%; 95% CI 22.5%-41.7%; p = 0.004) compared to the traditional UAS group, as determined by the one-side superiority test. Additionally, the S-UAS group exhibited a higher SFR at 3 months post-operation (87.5% versus 70.0%; RD 17.5%; 95% CI 8.7%-26.3%; p < 0.001), lower postoperative fever rate (RD -11.9%; 95% CI -18.7% to -4.9%; p < 0.001), reduced use of stone baskets (RD -70.6%; 95% CI -77.8% to -63.5%; p < 0.001), and better QoL improvement (MD 7.25; 95% CI 2.21-12.29; p = 0.005). No statistically significant differences were observed in operation time, hospital stay, or the need for second-stage RIRS. Interpretation: In RIRS for upper urinary tract stones ≤30 mm, S-UAS exhibited superior performance compared to traditional UAS, demonstrating higher SFR, reduced postoperative fever rate, and improved QoL outcomes. S-UAS emerges as a prudent and advantageous alternative to traditional UAS for RIRS. Funding: National Natural Science Foundation of China and Guangdong Province, and Zhejiang Medicine and Health Program.