Summary of findings: methenamine hippurate versus control (placebo or antiseptic iodine perineal wash) for the prevention of UTIa
| Certainty assessment | Patients, n | Effect | Certaintyb | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Studies, n | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Methenamine hippurate, n (%) | Control, n (%) | Relative RR (95% CI) | Absolute RR (95% CI) | |
| Patients remaining asymptomatic (follow-up: 6–12 months; assessed with number of patients that remained asymptomatic) | |||||||||||
| 2 | RCT | Seriousc | Very seriousd | Not serious | Seriouse | Publication bias strongly suspected f | 15/39 (38.5) | 14/33 (42.4) | 1.00 (0.27 to 3.66) | 0 fewer per 1000 (from 310 fewer to 1000 more) | Very low |
| Symptomatic UTI episodes (follow-up: 12 months; assessed with number of symptomatic UTI episodes) | |||||||||||
| 2 | RCT | Seriousc | Seriousg | Not serious | Seriouse | Publication bias strongly suspectedf | The pooled results of two RCTs on the number of symptomatic UTI episodes showed a non-statistically significant trend of benefit for methenamine hippurate with a total RR of 0.56 (95% CI = 0.13 to 2.35) with high heterogeneity (I2 93%) | Very low | |||
| Any adverse outcomes (follow-up: 12 months; assessed with number of patients with a reported adverse outcome) | |||||||||||
| 2 | RCT | Seriousc | Not serious | Not serious | Seriouse | Publication bias strongly suspected f | 6/55 (10.9) | 2/27 (7.4) | 1.32 (0.23 to 7.77) | 24 more per 1000 (from 57 fewer to 501 more) | Very low |
↵a Setting: community, outpatient, and primary care.
↵b GRADE Working Group grades of evidence — high: very confident that the true effect lies close to that of the estimate of the effect; moderate: moderately confident in the effect estimate — the true effect is likely to be close to the estimate of the effect but there is a possibllity that it is substantially different; low: confidence in the effect estimate is limited — the true effect may be substantially different from the estimate of the effect; very low: little confidence in the effect estimate — the true effect is likely to be substantially different from the estimate of effect.
↵c Allocation concealment and blindind of outcome assessment is unclear.
↵d High heterogeneity as each study compared methenamine hippurate against a different control group.
↵e Small sample size.
↵f Small number of studies hindered assessment of publication bias.
↵g High heterogeneity. CI = confidence interval. RCT = randomised controlled trial. RR = risk ratio. UTI = urinary tract infection.