Randomized Controlled Trial of Ultrasonic Propulsion-Facilitated Clearance of Residual Kidney Stone Fragments vs Observation.

PURPOSE

Ultrasonic propulsion is an investigational procedure for awake patients. Our purpose was to evaluate whether ultrasonic propulsion to facilitate residual kidney stone fragment clearance reduced relapse.

MATERIALS AND METHODS

This multicenter, prospective, open-label, randomized, controlled trial used single block randomization (1:1) without masking. Adults with residual fragments (individually ≤5 mm) were enrolled. Primary outcome was relapse as measured by stone growth, a stone-related urgent medical visit, or surgery by 5 years or study end. Secondary outcomes were fragment passage within 3 weeks and adverse events within 90 days. Cumulative incidence of relapse was estimated using the Kaplan-Meier method. Log-rank test was used to compare the treatment (ultrasonic propulsion) and control (observation) groups.

RESULTS

The trial was conducted from May 9, 2015, through April 6, 2024. Median follow-up (interquartile range) was 3.0 (1.8-3.2) years. The treatment group (n = 40) had longer time to relapse than the control group (n = 42; < .003). The restricted mean time-to-relapse was 52% longer in the treatment group than in the control group (1530 ± 92 days vs 1009 ± 118 days), and the risk of relapse was lower (hazard ratio 0.30, 95% CI 0.13-0.68) with 8 of 40 and 21 of 42 participants, respectively, experiencing relapse. Omitting 3 participants not asked about passage, 24 treatment (63%) and 2 control (5%) participants passed fragments within 3 weeks of treatment. adverse events were mild, transient, and self-resolving, and were reported in 25 treated participants (63%) and 17 controls (40%).

CONCLUSIONS

Ultrasonic propulsion reduced relapse and added minimal risk.

CLINICAL TRIAL REGISTRATION NO.: NCT02028559.