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Original Investigation
November 8, 2016

Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing HomesA Randomized Clinical Trial

Author Affiliations
  • 1Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
  • 2Section of Geriatrics, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
  • 3Yale Center for Analytical Sciences, Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut
JAMA. 2016;316(18):1879-1887. doi:10.1001/jama.2016.16141
Key Points

Question  Do cranberry capsules with sufficient proanthocyanidin content affect the presence of bacteriuria plus pyuria in older women living in nursing homes?

Findings  In this randomized clinical trial of 185 women nursing home residents, after adjusting for missing data and covariates, there was no statistically significant difference in presence of bacteriuria plus pyuria between the treatment (29.1%) and control (29.0%) groups over 1 year.

Meaning  Among older women living in nursing homes, cranberry capsules, compared with placebo, did not have a significant effect on the presence of bacteriuria plus pyuria over 1 year.

Abstract

Importance  Bacteriuria plus pyuria is highly prevalent among older women living in nursing homes. Cranberry capsules are an understudied, nonantimicrobial prevention strategy used in this population.

Objective  To test the effect of 2 oral cranberry capsules once a day on presence of bacteriuria plus pyuria among women residing in nursing homes.

Design, Setting, and Participants  Double-blind, randomized, placebo-controlled efficacy trial with stratification by nursing home and involving 185 English-speaking women aged 65 years or older, with or without bacteriuria plus pyuria at baseline, residing in 21 nursing homes located within 50 miles (80 km) of New Haven, Connecticut (August 24, 2012-October 26, 2015).

Interventions  Two oral cranberry capsules, each capsule containing 36 mg of the active ingredient proanthocyanidin (ie, 72 mg total, equivalent to 20 ounces of cranberry juice) vs placebo administered once a day in 92 treatment and 93 control group participants.

Main Outcomes and Measures  Presence of bacteriuria (ie, at least 105 colony-forming units [CFUs] per milliliter of 1 or 2 microorganisms in urine culture) plus pyuria (ie, any number of white blood cells on urinalysis) assessed every 2 months over the 1-year study surveillance; any positive finding was considered to meet the primary outcome. Secondary outcomes were symptomatic urinary tract infection (UTI), all-cause death, all-cause hospitalization, all multidrug antibiotic–resistant organisms, antibiotics administered for suspected UTI, and total antimicrobial administration.

Results  Of the 185 randomized study participants (mean age, 86.4 years [SD, 8.2], 90.3% white, 31.4% with bacteriuria plus pyuria at baseline), 147 completed the study. Overall adherence was 80.1%. Unadjusted results showed the presence of bacteriuria plus pyuria in 25.5% (95% CI, 18.6%-33.9%) of the treatment group and in 29.5% (95% CI, 22.2%-37.9%) of the control group. The adjusted generalized estimating equations model that accounted for missing data and covariates showed no significant difference in the presence of bacteriuria plus pyuria between the treatment group vs the control group (29.1% vs 29.0%; OR, 1.01; 95% CI, 0.61-1.66; P = .98). There were no significant differences in number of symptomatic UTIs (10 episodes in the treatment group vs 12 in the control group), rates of death (17 vs 16 deaths; 20.4 vs 19.1 deaths/100 person-years; rate ratio [RR], 1.07; 95% CI, 0.54-2.12), hospitalization (33 vs 50 admissions; 39.7 vs 59.6 hospitalizations/100 person-years; RR, 0.67; 95% CI, 0.32-1.40), bacteriuria associated with multidrug-resistant gram-negative bacilli (9 vs 24 episodes; 10.8 vs 28.6 episodes/100 person-years; RR, 0.38; 95% CI, 0.10-1.46), antibiotics administered for suspected UTIs (692 vs 909 antibiotic days; 8.3 vs 10.8 antibiotic days/person-year; RR, 0.77; 95% CI, 0.44-1.33), or total antimicrobial utilization (1415 vs 1883 antimicrobial days; 17.0 vs 22.4 antimicrobial days/person-year; RR, 0.76; 95% CI, 0.46-1.25).

Conclusions and Relevance  Among older women residing in nursing homes, administration of cranberry capsules vs placebo resulted in no significant difference in presence of bacteriuria plus pyuria over 1 year.

Trial Registration  clinicaltrials.gov Identifier: NCT01691430

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