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Evaluation of cranberry supplement for reduction of urinary tract infections in individuals with neurogenic bladders secondary to spinal cord injury. A prospective, double-blinded, placebo-controlled, crossover study

November 8, 2010
Linsenmeyer TA, Harrison B, Oakley A, Kirshblum S, Stock JA, Millis SR
J Spinal Cord Med 27(1):29-34

OBJECTIVE: To determine the effectiveness of cranberry supplement at preventing urinary tract infections (UTIs) in persons with spinal cord injury (SCI).

DESIGN: A prospective, double-blinded, placebo-controlled, crossover study.

PARTICIPANTS: 21 individuals with neurogenic bladders secondary to SCI.

MAIN OUTCOME MEASURES: Favorable or unfavorable response of cranberry supplement vs placebo on urinary bacterial counts and white blood cell (WBC) counts and the combination of bacterial and WBC counts.

METHODS: Individuals with neurogenic bladders due to SCI were recruited and randomly assigned to standardized 400-mg cranberry tablets or placebo 3 times a day for 4 weeks. After 4 weeks and an additional 1-week ""washout period,"" participants were crossed over to the other group. Participants were seen weekly, during which a urine analysis was obtained. UTI was defined as significant bacterial or yeast colony counts in the urine and elevated WBC counts (WBC count > or = 10 per high power field) in centrifuged urine. Participants with symptomatic infections were treated with appropriate antibiotics for 7 days and restarted on the cranberry tablet/ placebo after a 7-day washout period. Urinary pH between the cranberry and placebo groups was compared weekly. Data were analyzed using the Ezzet and Whitehead's random effect approach.

RESULTS: There was no statistically significant treatment (favorable) effect for cranberry supplement beyond placebo when evaluating the 2 treatment groups for bacterial count, WBC count, or WBC and bacterial counts in combination. Urinary pH did not differ between the placebo and cranberry groups.

CONCLUSION: Cranberry tablets were not found to be effective at changing urinary pH or reducing bacterial counts, urinary WBC counts, or UTIs in individuals with neurogenic bladders. Further long-term studies evaluating specific types of bladder management and UTIs will help to determine whether there is any role for the use of cranberries in individuals with neurogenic bladders.