SCI: Cranberry Juice and Urinary Tract Infections (2007)

Citation:

Reid G, Hsiehl J, Potter P, Mighton J, Lam D, Warren D, Stephenson J. Cranberry juice consumption may reduce biofilms on uroepithelial cells: pilot study in spinal cord injured patients.  Spinal Cord. 2001;39:26-30.

PubMed ID: 11224011
 
Study Design:
Non-Randomized Crossover Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To determine whether alteration of fluid intake and use of cranberry juice altered the bacterial biofilm load in the bladder.
Inclusion Criteria:

Spinal cord injury (SCI) patients with:

  • quadriplegia and paraplegia
  • over 18 years of age. 
  • previous history of urinary tract infection (UTI).
Exclusion Criteria:
  • Patients were not presently receiving antibiotics, 
  •  had normal renal function (serum creatinine > 110 umol/L, upper limit 90 umol/L),
  • did not have pyelonephritis,
  • were not pregnant, were not receiving prednisone or immunosuppressive drugs,
  • had no history of autonomic dysreflexia as a result of UTI in 12 months,
  • had no known urinary abnormality such as cancer or stone disease, and
  • did not have symptomatic UTI at time of study.
Description of Study Protocol:

Recruitment

 Not stated by author.

Design

 Patients followed their normal diet for seven days with an additional 250 mL of water at breakfast, lunch and dinner.  On day nine, the patients then continued their normal diet but added 250 mL of cranberry juice for seven days.

Blinding used (if applicable)

 N/A

Intervention (if applicable)

 Patients took a 250 mL glass of water in addition to their normal diet at breakfast, lunch, and dinner for seven days. On the ninth day, for another seven days, each patient drank a 250 mL glass of cranberry juice at the three meal times. The nurse monitored compliance and discussed any adverse events on days 7 and 15.  Urine samples were collected on day 0, 7 and 15 using the same collection protocol.

Statistical Analysis

 Not described by author.

Data Collection Summary:

Timing of Measurements

 Urine samples were given on day 0, 7 and 15 using the same collection protocol. The nurse monitored compliance or adverse events on days 7 and 15.

Dependent Variables

  • Presence of biofilms (percentage of cells with a biofilm present) on uroepithelial cells.

Independent Variables

  • 250 mL water at three meal times from days 1-7
  • 250 mL cranberry juice at three meal times for seven days (9 - 15)

 

Control Variables

 None noted by author

Description of Actual Data Sample:

 

Initial N: 15 participants were recruited, 4 females, 10 males and one subject was not described for age or sex.

Attrition (final N): 15 participants

Age: mean age = 42.3±14.9 years)

Ethnicity: Not discussed by author.

Other relevant demographics: Not discussed by author.

Anthropometrics:

N/A

Location:

 London, Ontario, Canada

Summary of Results:

Effects of cranberry juice consumption on the adherence of bacteria to uroepithelial cells

Variables

Day 0 (baseline)

Mean±SD

Day 7 (water)

Day 15 (cranberry juice)

P day 0 to 7 P day 0 to 15

Biofilm load %

20.26±25.5

 10.06±28.9

 5.62±7.03  0.36 0.013

Gram + bacteria

  3.08±5.2

   2.44±5.2

 0.67±1.34

 n/a 0.022

Gram - bacteria

  7.71±14.3

   9.93±16.9

 1.68±1.97

 n/a 0.054

 

Other Findings

 Cranberry juice intake caused a significant reduction in biofilm load compared to baseline (P=0.013) and to water treatment (P=0.028). 

Author Conclusion:
There is evidence to support the need for larger clinical trials into the use of cranberry juice to reduce the risk of UTI in a patient population highly suseptible to morbidity and mortality associated with drug resistant uropathogens.
Funding Source:
Industry:
Oceanspray Cranberries
Food Company:
Reviewer Comments:

Study was funded by Ocean Spray Cranberries, Lakeville, MA.

Demographics were not collected on one participant.

Small sample size.

Prevalence of men in the study.

Biofilm counts would likely have day to day variance regardless of treatment effects and may affect outcomes.

The laboratory did not provide accurate bacterial counts per mL, nor provide levels below 10000 per mL, or a breakdown of mixed bacterial species. Further studies are  needed to prove the efficacy of cranberry juice. Other parameters in addition to urine cultures need to be examined.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? ???
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? Yes
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? Yes
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? Yes
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? No
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? No
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? No
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? No
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? No