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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Cranberry is not effective for the prevention or treatment of urinary tract infections in individuals with spinal cord injury

EA Opperman.

Review published: 2010.

Link to full article: [Journal publisher]

CRD summary

The review found that limited evidence suggested that cranberry (in juice or supplement form) did not seem to be effective in preventing or treating urinary tract infections in people with spinal cord injury. The author's cautious conclusion reflected the evidence presented, but its reliability is uncertain due to weaknesses in the review process.

Authors' objectives

To assess the effectiveness of cranberry for the prevention or treatment of urinary tract infections in people with spinal cord injury.

Searching

The MEDLINE database was searched; search terms were reported. Reference lists of suitable publications were scanned for additional articles.

Study selection

Studies that evaluated the use of cranberry (in supplement or juice form) for the prevention or treatment of urinary tract infections in people with spinal cord injury (paraplegia or tetraplegia) were eligible for inclusion.

Most of the included studies reported using cranberry extract tablets alone; the remaining studies reported using cranberry extract tablet and methenamine hippurate, or cranberry juice. All studies compared cranberry with placebo. Doses of cranberry varied between studies. Duration of treatment ranged from seven days to six months (where reported). Participants had spinal cord injury together with neurogenic bladder, stable bladder management, or history of urinary tract infections. The average age of participants ranged from 41 to 52 years; most were male. The proportion of participants with paraplegia or tetraplegia varied between studies, as did completeness of injury and bladder management strategies. Outcomes in the included studies were incidence of urinary tract infections, urinary bacterial counts, white blood cell counts, combination of bacterial and white blood cell counts, biofilm coating, and bacterial adhesion.

The author did not state how many reviewers performed the selection of studies.

Assessment of study quality

The author did not state that they formally assessed validity, although some details relating to study design and drop-out rates were reported in the review.

Data extraction

P-values, as reported by the studies, were extracted for most outcomes, along with the numbers of participants with adverse reactions.

The author did not state how many reviewers performed the data extraction.

Methods of synthesis

Studies were grouped into either prevention or treatment categories and reported in a narrative synthesis.

Results of the review

Five studies (n=436 participants; range 15 to 305) were included in the review: four randomised controlled trials (RCTs) and one pilot study. Two RCTs were cross-over in design, one RCT had a factorial design, and one pilot study had an open cross-over design. Some studies reported details of withdrawals and drop-outs.

Urinary tract infection prevention (four studies): Cranberry significantly reduced biofilm load compared to baseline (p=0.013; one cross-over pilot study). One RCT reported a reduction in the likelihood of urinary tract infections (p<0.05) due to a reduction in adhesion of Gram-negative (p=0.05) and Gram-positive (p=0.002) bacteria while receiving cranberry compared with placebo. The same study also reported a reduction in the incidence of significant bacteriuria for those receiving cranberry compared with placebo (p=0.01). There were no statistically significant differences between cranberry tablets and placebo for other urinary outcomes (two RCTs). Only two studies reported adverse reactions; these were reported to be mild (diarrhoea, constipation, nausea, rash, and abdominal discomfort).

Urinary tract infection treatment (one RCT): There were no significant differences between cranberry and placebo groups for urine specimens with bacterial counts, types and numbers of bacterial species, number of urinary leukocytes, urinary pH, or episodes of symptomatic urinary tract infection. Some participants appeared to withdraw from the intervention group due to adverse events (details not reported).

Authors' conclusions

Limited evidence from clinical trials of variable design suggested that cranberry, in juice or supplement form, did not seem to be effective in preventing or treating urinary tract infections in people with spinal cord injury. More rigorous clinical research is needed to confirm this.

CRD commentary

The review question was adequately defined with broad inclusion criteria. Only one database was searched; search dates were not reported; it was unclear whether efforts were made to reduce language or publication bias, so some relevant studies may have been missed. Review methods were not reported (and there was only one author of the review), so it was unknown whether appropriate measures were taken to reduce reviewer error and bias.

No formal quality assessment was undertaken of the included studies, although some aspects of study design were reported, but it was not possible to determine the reliability of the results. A narrative synthesis was appropriate given the differences between the studies for participants, interventions and outcomes.

The author's cautious conclusion reflected the evidence presented, but its reliability is uncertain due to weaknesses in the review process.

Implications of the review for practice and research

Practice: The author did not state any implications for practice.

Research: The author stated that more rigorous clinical research is needed to enable generalisability to the adult population with spinal cord injury in terms of demographics, level of injury, traumatic and non-traumatic injury and various types of bladder management. Future studies should include large sample sizes, report drop-outs, be of longer duration, investigate different doses of cranberry, and use various methods to observe effects of cranberry in preventing urinary tract infections (urine cultures, bacteria counts, white blood cell counts). Adverse effects should also be investigated. A standardised definition of urinary tract infection is required on which to base conclusions of the effectiveness of cranberry on urinary tract infections.

Funding

Not stated.

Bibliographic details

Opperman EA. Cranberry is not effective for the prevention or treatment of urinary tract infections in individuals with spinal cord injury. Spinal Cord 2010; 48(6): 451-456. [PubMed: 19935757]

Indexing Status

Subject indexing assigned by NLM

MeSH

Animals; Beverages; Clinical Trials as Topic /methods /statistics & numerical data; Female; Humans; MEDLINE /statistics & numerical data; Male; Phytotherapy; Plant Preparations /therapeutic use; Spinal Cord Injuries /complications; Urinary Tract Infections /etiology /prevention & control; Vaccinium macrocarpon

AccessionNumber

12010004451

Database entry date

13/04/2011

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 19935757

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