Cranberry for prevention of pyuria and bacteriuria

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Juthani-Mehta M, et al. "Effect of cranberry capsules on bacteriuria plus pyuria among older women in nursing homes: A randomized clinical trial". JAMA. 2016. 316(18):1879-1887.
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Clinical Question

Among older women residing in nursing homes, does administration of cranberry capsules vs. placebo decrease bacteriuria plus pyuria?

Bottom Line

Among female nursing home residents with age ≥65, administration of cranberry capsules was not associated with a reduction of bacteriuria plus pyuria when compared to placebo.

Major Points

Women aged ≥65 are at high risk for bacteriuria plus pyuria. The risk for these women is increased while living in a nursing home. Cranberry products have been used to decrease risk of urinary tract infections (UTIs), but there is little clinical evidence to support this strategy. While UTI is a clinical diagnosis with variability based upon diagnostic approach, bacteriuria and pyuria are objective findings thought to be on the causal pathway of UTI. Should cranberry capsules reduce incident pyuria and bacteriuria among high risk women, this would potentially support its use in prevention of UTI.

Published in 2016 by Juthani-Mehta and colleagues, this study randomized 185 women age ≥65 living in nursing homes with and without a history of bacteriuria plus pyuria to cranberry capsules or placebo for 360 days. At the end of the follow-up period, rates of bacteriuria plus pyuria was similar between groups. There was no difference in the rate of symptomatic UTIs between groups.

This finding of this study is consistent with other evidence. In particular, a 2012 Cochrane review[1] found that cranberry products do not reduce the risk of urinary tract infections in susceptible patients. The current study provides further evidence that cranberry products have no benefit in preventing bacteriuria plus pyuria in older nursing home women. The findings by the study by Juthani-Mehta and colleagues further supports these findings.

Of note, this trial included incident UTIs as a secondary outcome. There were few UTIs in each group.

Guidelines

As of April 2017, no guidelines have been published that reflect the results of this trial.

Design

  • Double-blind, randomized, placebo-controlled efficacy trial
  • N=185
    • Cranberry capsules (n=92)
    • Placebo (n=93)
  • Setting: 21 nursing homes in Connecticut
  • Enrollment: 2012-2015
  • Mean follow-up: every 2 months for 1 year
  • Analysis: Intention-to-treat
  • Primary Outcome: Presence of bacteriuria plus pyuria

Population

Inclusion Criteria

  • Female
  • Long-term care residents
  • English speaking
  • Age ≥65 years

Exclusion Criteria

  • Short-term residents
  • Suppressive antibiotics or other anti-infective therapies for recurrent UTI
  • ESRD
  • Unable to produce a baseline clean catch urine specimen
  • Warfarin therapy
  • Prior nephrolithiasis
  • Indwelling bladder catheter
  • Allergy to cranberry products
  • Treatment with cranberry products
  • Nursing home residence for less than 4 weeks

Baseline Characteristics

  • Demographics: Age 86 years, White race 90%, Hispanic 3%
  • Coexisting Conditions: Hypertension 82%, dementia 78%, psychiatric disorder 68%, connective tissue disease 60%, DM 28%, other endocrine disorder 47%, CAD 32%, HF 31%, COPD 22%, CKD 22%, arrhythmia 20%
  • Bacteriuria plus pyuria: 31%
  • Incontinence: Bladder 68%, bowel 44%
  • Prior infections:
    • Episodes of UTIs in past year: 0 (69%), 1 (22%), 2 (6%), ≥3 (3%)
    • Courses of antibiotics in past year: 0 (42%), 1 (29%), 2 (14%), ≥3 (15%)
  • Functional and behavioral Status
    • Number of ADLs in prior 7 Days: 0 (68%), 1-4 (26%), 5-8 (6%)
    • Number of prescribed medications (median): 10

Interventions

  • Randomized a group:
    • Cranberry - Two oral cranberry capsules with 36 mg of the active ingredient proanthocyanidin, administered once dialy
    • Placebo
  • Follow-up every 2 months for 1 year for clean catch urine specimens.

Outcomes

Presented as cranberry vs. placebo.

Primary Outcomes

Bacteriuria plus pyuria
This was adjusted for baseline bacteriuria, incontinence, age at enrollment, and number of comorbidities. The authors imputed missing data.
29.1% vs. 29.0% (OR 1.01; 95% CI 0.61-1.66; P=0.98)

Secondary Outcomes

Symptomatic UTI
10 vs. 12 events
All-cause mortality
20.4% vs. 19.1%/100 P-Y (RR 1.07; 95% CI 0.54-2.12; P=0.84)
All-cause hospitalization
39.7% vs. 59.6%/100 P-Y (RR 0.67; 95% CI 0.32-1.40; P=0.28)
MDR antibiotic-resistant gram negative bacilli
10.8% vs. 28.6%/100 P-Y (RR 0.38; 95% CI 0.10-1.46; P=0.16)
Administration of antibiotics for presumed UTI
8.3% vs. 10.8%/100 P-Y (RR 0.77; 95% CI 0.44-1.33; P=0.34)
Total antibiotic administration
17.0% vs. 22.4%/100 P-Y (RR 0.76; 95% CI 0.46-1.25; P=0.28)

Adverse Events

Any
1791 vs. 2039
Serious
60.1% vs. 78.6%/100 P-Y
Related to the study protocol: None in either group

Criticisms

  • Greater than 20% of patients were lost to follow-up evenly split between groups, which could impact the outcome.
  • To account for the loss to follow-up, the primary outcome was analyzed using imputations and adjustments for baseline characteristics.
  • Few UTI events in both groups.
  • Of 5045 patients that were assessed for eligibility, only 185 were included in the study and randomized.

Funding

  • The cranberry capsules were donated and manufactured by Pharmatoka.
  • National Institute of Aging, National Institutes of Health.
  • Claude D. Pepper Older Americans Independence Center

Further Reading

  1. Jepson RG et al. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev 2012. 10:CD001321.