Five RCTs (n=1,407) were included in the meta-analysis. Two trials received a Jadad score of 2, two scored 3 and one scored four. All RCTs were double-blinded.
Clinical success was significantly higher in patients treated with antibiotics than placebo (OR 4.81, 95% CI 2.51 to 9.21; four trials, n=1,062). This was particularly noted for cure (OR 4.67, 95% CI 2.34 to 9.35, p<0.0001).
Microbiological success at the end of treatment was significantly higher in the treatment group (OR 10.67, 95% CI 2.96 to 38.43, p=0.0003; three trials, n=967). The direction of effect remained after the end of treatment (OR 5.38, 95% CI 1.63 to 17.77, p=0.006; three trials, n=738). There was significant heterogeneity in both analyses (I2=82%, p=0.004 and I2=76%, p=0.01).
Re-infection or relapse after the end of treatment was significantly more likely in the placebo group after the end of treatment (OR 0.27, 95% CI 0.13 to 0.55; five trials, n=843). There was no significant difference in the incidence of pyelonephritis (two trials, n=962) or in emergence of resistance (three trials, n=173) between treatment and placebo groups.
Adverse events were more likely to occur in women treated with antibiotics compared with placebo (OR 1.64, 95% CI: 1.10 to 2.44, p=0.01; four trials, n=1,069). There was no significant heterogeneity. There was no significant difference between groups in terms of withdrawals due to adverse events.