Richard Foon, Philip Toozs‐Hobson, Pallavi Latthe

There is a risk that people who have invasive urodynamic studies (cystometry) will develop urinary tract infections or bacteria in the urine or blood. However, the use of prophylactic antibiotics before or immediately after invasive cystometry or urodynamic studies is not without risks of adverse effects and emergence of resistant microbes. To assess the effectiveness and safety of administering prophylactic antibiotics in reducing the risk of urinary tract infections after urodynamic studies. The hypothesis was that administering prophylactic antibiotics reduces urinary tract infections after urodynamic studies. We searched the Cochrane Incontinence Group Specialised Trial Register, MEDLINE (January 1966 to January 2009), CINAHL (January 1982 to January 2009), EMBASE (January 1966 to January 2009), PubMed (1 January 1980 to January 2009), LILACS (up to January 2009), TRIP database (up to January 2009), and the UK NHS Evidence Health Information Resources (searched 10 December 2009). We searched the reference lists of relevant articles, the primary trials and the proceedings of the International Urogynaecological Association International Continence Society and the American Urological Association for the years 1999 to 2009 to identify articles not captured by electronic searches. There were no language restrictions. All randomized controlled trials and quasi-randomized trials comparing the use of prophylactic antibiotics versus a placebo or no treatment in patients having urodynamic studies were selected. Two authors (PL and RF) independently performed the selection of trials for inclusion and any disagreements were resolved by discussion. All assessments of the quality of trials and data extraction were performed independently by two authors of the review (PL and RF) using forms designed according to Cochrane guidelines. We attempted to contact authors of the included trials for any missing data. Data were extracted on characteristics of the study participants including details of previously administered treatments, interventions used, the methods used to measure infection and adverse events.Statistical analyses were performed according to Cochrane Collaboration guidelines. Data from intention-to-treat analyses were used where available. For the dichotomous data, results for each study were expressed as a risk ratio (RR) with 95% confidence interval (CI) and combined for meta-analysis using the Mantel-Haenszel method.The primary outcome was urinary tract infection. Heterogeneity was assessed by the P value and I(2) statistic. Nine randomized controlled trials involving the prophylactic use of antibiotics in patients having urodynamic studies were identified and these included 973 patients in total; one study was an abstract. Two further trials were excluded from the review. The methods of the included trials were poorly described.The primary outcome in all trials was the rate of developing significant bacteriuria, defined as the presence of more than 100,000 bacteria per millilitre of a mid-stream urine sample on culture and sensitivity testing. The other outcomes included pyrexia, haematuria, dysuria and adverse reactions to antibiotics.The administration of prophylactic antibiotics when compared to a placebo reduced the risk of significant bacteriuria (4% with antibiotics versus 12% without, risk ratio (RR) 0.35, 95% CI 0.22 to 0.56) in both men and women. The administration of prophylactic antibiotics also reduced the risk of haematuria (RR 0.46, 95% CI 0.23 to 0.91). However, there was no statistically significant difference in the primary outcome, risk of symptomatic urinary tract infection (40/201, 20% versus 59/214, 28%; RR 0.73, 95% CI 0.52 to 1.03); or in the risk of fever (RR 5.16, 95% CI 0.94 to 28.16) or dysuria (RR 0.83, 95% CI 0.5 to 1.36). Only two of 135 people had an adverse reaction to the antibiotics. The number of patients needed to treat with antibiotics to prevent bacteriuria was 12.3. Amongst women, the number needed to treat to prevent bacteriuria was 13.4; while amongst men it was 9.1 (number needed to treat = 1/ absolute risk reduction). Prophylactic antibiotics did reduce the risk of bacteriuria after urodynamic studies but there was not enough evidence to suggest that this effect reduced symptomatic urinary tract infections. There was no statistically significant difference in the risk of fever, dysuria or adverse reactions. Potential benefits have to be weighed against clinical and financial implications, and the risk of adverse effects.