By Barbara Greenwood Dufour
Urinary tract infections (UTIs) are the second most common infection of the human body. Certain medical conditions, such as bladder dysfunctions and urologic anatomical abnormalities, increase one’s risk of developing a UTI, as does being a resident of a long-term care facility or using a urinary catheter. However, healthy women are also at an increased risk. According to US statistics, of the general healthy female population, approximately 50 per cent will experience at least one UTI in their lifetime, and up to half of women who develop a UTI will have a recurrence within a year. For postmenopausal women, particularly those with an estrogen deficiency, that risk is even higher.
Antibiotics are commonly used for the treatment of UTIs, and they’ve also been used as a preventive measure for populations at an increased risk of recurrent UTIs. However, concerns regarding antimicrobial resistance, the potential impact on the human microbiome, as well as the related side effects and cost of antibiotics have led to an interest in non-antibiotic UTI prevention strategies. Two such alternatives are topical estrogen (e.g., vaginal estrogen suppositories, cream, tablets, and extended-release inserts) and cranberry products (e.g., cranberry juice, extract, and capsules). Topical estrogen deals directly with the issue of estrogen deficiency. The idea behind this treatment is that, since decreased estrogen can change the vaginal flora and make it more susceptible to bacteria, adding estrogen can normalize the flora and reduce the risk of a UTI. Cranberries have been used to address urological health issues for hundreds of years. It’s thought that a group of compounds found in cranberries, called proanthocyanidins, can stop antibiotic-susceptible and ‑resistant strains of bacteria from adhering to the cells of the urinary tract, thereby preventing an infection.
To find out what the evidence says about the effectiveness of topical estrogen and cranberry products for preventing UTIs, CADTH — an independent agency that finds, assesses, and summarizes the research on drugs, medical devices, tests, and procedures — looked for the available evidence on the topic. Two systematic reviews on topical estrogen prophylaxis in women were identified. For cranberry product prophylaxis, three systematic reviews, two of which also included meta-analyses; eight randomized controlled trials; and five non-randomized studies were identified.
Both systematic reviews that looked at topical estrogen for UTI prophylaxis in women found evidence to support its effectiveness. One of the reviews, which examined studies involving menopause patients, concluded that vaginal estrogen reduces the incidence of UTI. The other, which examined evidence pertaining to community dwelling, post-menopausal women, identified two studies that reported a statistically significant reduction in UTI incidence associated with vaginal estrogen prophylaxis. Neither review reported any adverse effects from this treatment.
One of the systematic reviews with a meta-analysis that looked at cranberry products found them to be potentially effective in women with recurrent UTIs and in children, and another systematic review that looked specifically at a pediatric population also found evidence of effectiveness in children. In seven of the eight randomized controlled trials and in all five of the non-randomized studies, statistically significant reductions in UTIs were reported in a variety of patient subpopulations, such as post-gynecological surgery patients and elderly long-term care residents at a high risk of developing UTIs. The other systematic review with a meta-analysis, however, concluded that cranberry products are no more effective than placebo or no treatment for women with recurrent UTIs, children, and a variety of additional subpopulations. The conflicting findings of this systematic review compared with the others could be due to variations in the patient populations and in the types of cranberry products examined in the studies. There were no reports of any significant adverse events specific to this intervention.
The literature CADTH identified on topical estrogen for UTI prevention consistently supports its effectiveness in women. Regarding cranberry products, much of the literature suggests such products could be an effective for preventing UTIs in certain at-risk subpopulations, but more evidence is needed. However, given that cranberry products are so readily available and there appear to be no significant risks in using them, they might be a non-antibiotic treatment option to consider.
If you’d like to learn more about the evidence on topical estrogen and cranberry products for preventing UTIs, or about CADTH and the evidence we offer to help guide health care decisions in Canada, visit www.cadth.ca, follow us on Twitter @CADTH_ACMTS, or talk to a Liaison Officer in your region: www.cadth.ca/contact-us/liaison-officers.
Barbara Greenwood Dufour is a Knowledge Mobilization Officer at CADTH.