Comparison of treatment outcomes according to output voltage during shockwave lithotripsy for ureteral calculi: a prospective randomized multicenter study

Abstract

Purpose: To investigate the effect of fixed versus escalating voltage during SWL on treatment outcomes in patients with ureteral calculi (UC).

Methods: A prospective, randomized, multicenter trial was conducted on 120 patients who were diagnosed with a single radiopaque UC. The patients were randomized into group C (n = 60, constant 13 kV, 3,000 shock wave, 2 Hz) or group E (n = 60, 11.4-12.0-13 kV per 1,000 shock waves, 2 Hz). They were evaluated by plain abdominal radiography and urinalysis at 1 week after a single session of SWL, and repeat SWL was performed if needed. The primary endpoint was stone-free rate at 1 week (SFR1) after SWL. Secondary endpoints were post-SWL visual pain score (VPS), oral analgesic requirements during 1 week, and cumulative SFRs after the second and third sessions of SWL.

Results: Groups C and E were well balanced in terms of baseline patients and stone characteristics, including pre-SWL VPS, stone location, and stone size (6.24 ± 1.92 vs. 6.30 ± 2.13 mm). SFR1s were not significantly different between groups C and E (60.0 vs. 68.3%, p = 0.447). Analyses stratified by stone size (<6 vs. ≥6 mm) showed no difference in SFR1 (p = 0.148 vs. 0.808). In the analyses stratified by stone location, group E tended to be more effective in distal UC (81.0 vs. 50.0%, p = 0.052), whereas no difference was seen in proximal UC (p = 0.487). Secondary endpoints were also similar between the two groups.

Conclusions: Our results suggest that voltage escalation during SWL in UC may not provide superior stone fragmentation compared to fixed voltage.