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Review: cranberry products may prevent urinary tract infection in women with recurrent infections

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R Jepson

Dr R Jepson, University of Stirling, Stirling, UK; ruth.jepson{at}stir.ac.uk

QUESTION

Do cranberry products prevent urinary tract infection (UTI) in susceptible people?

REVIEW SCOPE

Studies selected compared cranberry juice or cranberry tablets (taken for ⩾1 mo) with placebo, no treatment, or other treatments for primary or secondary prevention of UTI in susceptible populations (eg, people who had recurrent UTIs, were elderly, or required catheterisation). Studies involving treatment of active UTI were excluded. Outcome was symptomatic UTI with bacteriological confirmation.

REVIEW METHODS

Cochrane Renal Group trials register and Cochrane Central Register of Controlled Trials (to Jan 2007), Cochrane Collaboration Field in Complementary Medicine trials register, Medline, CINAHL, EMBASE/Excerpta Medica, LILACS, PsycLit, Biological Abstracts, Current Contents, National Research Register, the internet, reference lists, and conference abstracts were searched for randomised or quasi-randomised controlled trials published in English or 1 of 7 European languages. Companies involved with cranberry products were consulted. 10 trials (n = 1049) met the selection criteria: 3 trials of women with recurrent UTI (n = 319), 3 trials of elderly people (n = 606), 2 trials of children with neuropathic bladder requiring intermittent catheterisation (n = 55), and 2 trials of patients with spinal cord injury (n = 69). 4 trials had adequate allocation concealment, and 7 were double blinded. Dropout rates ranged from 0 to 55% (median 33%).

MAIN RESULTS

Meta-analysis of 4 trials showed that cranberry products reduced risk of UTI overall and in the subgroup of women with recurrent UTIs (table). Of the 6 trials not included in the meta-analysis, 3 crossover trials of children and adults needing catheterisation showed no benefit of cranberry products for preventing symptomatic UTI; 2 trials of elderly people did not report this outcome. In the other study, a crossover trial, 10 women with recurrent UTIs had fewer symptomatic UTIs while taking cranberry capsules for 3 months than while taking placebo (p<0.005).

Cranberry products v placebo or no treatment (control) to prevent urinary tract infection (UTI) at 6–12 months*

CONCLUSIONS

Cranberry products may prevent urinary tract infection (UTI) in women with recurrent UTIs but do not seem to be beneficial in people requiring urinary catheterisation. Evidence for use in elderly people is inconclusive.

ABSTRACTED FROM

Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev 2008;(1):CD001321.

Clinical impact ratings: Family/general practice 6/7; Paediatrics 5/7

Commentary

Symptomatic UTI is common, and recurrent UTIs are a problem for many people. Complications, such as pyelonephritis and sepsis, contribute to morbidity, especially in people who are elderly or immunocompromised. Prevention of UTIs can reduce patient discomfort, improve quality of life, and decrease healthcare costs.

Given recent interest in the use of cranberry products for prevention and management of UTIs, the systematic review by Jepson and Craig is timely and relevant. The authors conducted a comprehensive search for published and unpublished randomised trials, including non-English literature. Trials were independently appraised using standard criteria, and results were clearly described. Meta-analysis was correctly limited to the trials with data amenable to such analysis (eg, crossover trials were not included).

Meta-analysis showed that people taking cranberry products were less likely to have recurrent UTIs than those taking placebo, overall and in women with recurrent UTIs. Because statistically significant or clinically meaningful differences were not shown in the other target groups, a general conclusion about cranberry product effectiveness cannot be drawn. High dropout rates occurred because of gastrointestinal complaints or taste, calories, or cost of cranberry products; therefore, lack of acceptability is likely to limit the potential success of this simple intervention. Finally, because of differences in the cranberry products tested, their doses, and treatment duration, it is impossible to draw conclusions about which regimen is most effective.

In summary, the evidence suggests that cranberry products are not effective for individuals with neuropathic bladder but may be effective in women with recurrent UTIs. Further research is required to establish optimal doses and dosing schedules and effectiveness in elderly people. Until such evidence is available, one can cautiously recommend cranberry products to women with recurrent UTIs, suggesting that they assess which products, doses, and durations, if any, work for them. Such an approach can only be recommended on an individual basis and in conjunction with use of other currently recommended preventive strategies.

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Footnotes

  • Source of funding: Nuffield Trust.

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