A Multicenter Randomized Controlled Trial of Antimicrobial Prophylaxis to Prevent Urinary Tract Infections after Shockwave Lithotripsy for Urolithiasis: The APPEAL Trial

Abstract

Background and objective: Shockwave lithotripsy (SWL) carries a risk of postprocedural infection. Use of antibiotic prophylaxis by clinicians is variable and international guidelines provide conflicting recommendations, reflecting low-certainty evidence. We investigated whether antibiotic prophylaxis reduces bacteriuria and post-SWL urinary tract infections (UTIs).

Methods: APPEAL, an international multicenter, blinded trial, randomized adults undergoing SWL for urolithiasis to a single dose of ciprofloxacin or placebo. The primary outcome was the incidence of a composite of bacteriuria or symptomatic UTI after SWL. Other outcomes included the incidence of pyelonephritis or urosepsis.

Key findings and limitations: Of the 1722 randomized patients, 28 underwent postrandomization exclusions (mainly nonvisualizable stones). Among the analysis population (n = 1694; median age 50 yr; 30% female), 74% had kidney stones and 26% had ureteral stones. Bacteriuria (without symptoms) or symptomatic UTI occurred in 20 patients (2.7%) in the ciprofloxacin arm and 30 (3.9%) in the placebo arm (risk ratio [RR] 0.68, 95% confidence interval [CI] 0.41-1.15). Symptomatic UTI occurred in ten patients (1.3%) in the ciprofloxacin arm and 21 (2.7%) in the placebo arm (RR 0.49, 95% CI 0.19-1.23). No patients in the ciprofloxacin arm and nine (1.2%) in the placebo arm developed pyelonephritis (RR 0.05, 95% CI 0.003-0.93). No patients developed urosepsis and no serious adverse events occurred.

Conclusions and clinical implications: A single dose of ciprofloxacin reduced the risk of post-SWL pyelonephritis, with a modest absolute benefit. The patient importance of this reduction depends on individual preferences in weighing a small absolute reduction in risk against the potential harms and resistance-related implications of antibiotic use. Results from the APPEAL trial will inform global practice and support evidence-based decision-making for patients undergoing SWL.

Keywords: Antibiotic prophylaxis; Clinical trials; Lithotripsy; Randomized controlled trial; Urinary tract infection; Urolithiasis.