The Efficacy and Safety of Radiation-Free Retrograde Intrarenal Surgery: A Prospective Multicenter-Based, Randomized, Controlled Trial

Abstract

Purpose: Fluoroscopy is usually required during retrograde intrarenal surgery (RIRS). Although fluoroscopy is considered necessary for effective and safe RIRS, there is growing awareness regarding radiation exposure risk to patients and surgeons. We conducted a multicenter-based, randomized, controlled trial to compare the safety and effectiveness of radiation-free (RF) RIRS with radiation-usage (RU) RIRS for kidney stone management.

Materials and Methods: From August 2020 to April 2022, patients with a unilateral kidney stone (≤20 mm) eligible for RIRS were prospectively enrolled in 5 tertiary medical centers after randomization and divided into the RF and RU groups. RIRS was performed using a flexible ureteroscope with a holmium:YAG laser. The primary end point of this study was the success rate, defined as complete stone-free or residual fragments with asymptomatic kidney stones ≤ 3 mm. The secondary end point of this study was ascertaining the safety of RF RIRS. The success rates were analyzed using a noninferiority test.

Results: Of the 140 consecutive randomized participants, 128 patients completed this study (RF: 63; RU: 65). The success rates (78% vs 80%, P = .8) were not significantly different between the groups. The rate of high-grade (grade 2-4) ureter injury was not significantly higher in the RF group compared to the RU group (RF = 3 [4.8%] vs RU = 2 [3.1%], P = .6). In RF RIRS, the success rate was noninferior compared to RU RIRS (the difference was 2.2% [95% CI, 0.16-0.12]).

Conclusions: This study demonstrated that the surgical outcomes of RF RIRS were noninferior to RU RIRS. Significant innovative changes in the treatment of kidney stones have occurred in the last 30 years, including extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, and retrograde intrarenal surgery (RIRS).1 Despite these changes, the essential goals of kidney stone management remain the same: maximize stone-free rate (SFR) and minimize surgery-related morbidity. Recently, RIRS has especially become popular in stone management for several reasons, including minimal invasiveness, patients’ early discharge, lower complication rates, and favorable success rates.2 In general, RIRS has been performed under fluoroscopy guidance. The radiation exposure during RIRS with the frequent use of fluoroscopy can cause potentially harmful effects to patients and surgeons. Ionizing radiation is mainly concerned with cancer risk that develops due to cellular damage and the expression of affected nuclear material.3 Therefore, decreasing unnecessary radiation exposure as well as ensuring the success rate of RIRS should be key points for protecting patients and surgeons. Radiation-free (RF) RIRS has been described in adult and pediatric urology.1,4-7 However, there are no prospective, multicenter-based, randomized, controlled trials (RCTs) comparing the success rates or safety between radiation-usage (RU) and RF RIRS. We hypothesized that RF RIRS is noninferior to RU RIRS and compared the safety and efficacy of RF RIRS with RU RIRS using a multicenter-based RCT.