The antiseptic methenamine hippurate works as well as low-dose antibiotics for preventing recurrent urinary tract infections (UTIs) in women, a randomised non-inferiority trial has found.
Systematic reviews had concluded that methenamine hippurate could prevent UTIs, but recognised the need for further large, randomised trials to clarify the findings.
In this open-label trial published in The BMJ, researchers recruited 240 women from eight UK secondary care centres and randomised them to 1mg methenamine hippurate taken orally twice daily for 12 months, or antibiotic prophylaxis with either nitrofurantoin (50 or 100mg), trimethoprim (100mg), or cefalexin (250mg) taken orally once a day for 12 months.
On average, the women were aged 50 years, with 59% peri/post-menopausal and with the group having experienced a median average of six UTIs in the 12 months before the trial.
Researchers found the incidence of antibiotic-treated UTIs during the 12-month treatment period was 0.89 episodes per person year in the antibiotics group and 1.38 in the methenamine hippurate, with an absolute difference of 0.49, confirming non-inferiority.
‘Our results could support a change in practice in terms of preventive treatments for recurrent UTI and provide patients and clinicians with a credible alternative to daily antibiotics, giving them confidence to pursue strategies that avoid long-term antibiotic use,’ the researchers wrote.
The adverse event rate was low, they noted, with only two serious adverse events classified as possibly or probably related to trial drug treatment and both occurred in the antibiotic arm.
The rates of hospital admission for UTI (four participants) and febrile UTI (six participants) were low, the researchers reported, but all occurred in the methenamine hippurate arm.
An accompanying editorial said the results needed cautious interpretation, but they aligned with other studies and increased the confidence with which methenamine hippurate could be offered as an option to women needing prophylaxis against recurrent UTI.
‘Whether the non-inferiority margin (one episode of urinary tract infection) used in this trial was of the right magnitude to capture any clinically meaningful difference between treatments will likely inspire debate,’ the Australian researchers wrote in the editorial.
‘However, we agree with the authors that decisions on preventive treatment for recurrent urinary tract infection are well suited to shared decision making, where options are presented, the benefits and harms of each option are discussed, and each patient’s values and preferences are considered before patients and clinicians decide together on the next steps. [This] trial will help to inform this important conversation.’