To determine the efficacy and cost-effectiveness of routine antimicrobial prophylaxis prior to shock wave lithotripsy (SWL) in patients with a sterile pretreatment urine culture.

A structured MedLine search revealed eight prospective, randomized, controlled trials (RCTs) of active treatment versus placebo or no treatment (n = 885) and six clinical series (non-RCTs; n = 597) addressing the use of antimicrobial prophylaxis for SWL. A meta-analysis was performed on the eight RCTs, with the primary outcome being the diagnosis of a urinary tract infection (UTI) post-SWL. A cost analysis was performed comparing a prophylactic strategy (prophylaxis for every patient and treatment for post-SWL UTIs) with a treatment-only strategy for post-SWL UTIs using various antimicrobial combinations and the median probability of post-SWL UTIs determined by meta-analysis.

The incidence of post-SWL UTIs ranged from 0% to 28% in the control group and from 0% to 7.7% in the patients who underwent prophylaxis. Combining the placebo/no-drug treatment arms in the six RCTs by meta-analysis (Bayesian analysis) resulted in a median probability of a post-SWL UTI of 5.7% (95% confidence interval [CI]3.8% to 8.4%). For the drug treatment arms, the median probability of a UTI was 2.1% (95% CI 0.9% to 3.6%). Relative risk (RR) analysis resulted in an overall RR of post-SWL UTIs with prophylaxis versus without prophylaxis of 0.45 (95% CI 0.22 to 0.93) (P = 0.0005). Depending on the antimicrobial regimen used for prophylaxis and treatment, a prophylactic strategy added minimally to the overall treatment cost of SWL, and proved cost beneficial when taking into consideration serious UTIs requiring inpatient treatment.

A policy of antibiotic prophylaxis prior to SWL in patients with sterile pretreatment urine cultures is efficacious in reducing the rate of post-SWL UTIs. Discounting inpatient episodes for sepsis and acute pyelonephritis, however, the strategy is not cost-effective. In contrast, using literature-derived incidence estimates for post-SWL urosepsis or pyelonephritis necessitating inpatient treatment, prophylaxis becomes both efficacious and cost-effective, and thus constitutes a dominant strategy.