Cranberry-containing products for prevention of urinary tract infections in susceptible populations: a systematic review and meta-analysis of randomized controlled trials.
BACKGROUND
Urinary tract infection (UTI) is one of the most commonly acquired bacterial infections. Cranberry-containing products have long been used as a folk remedy to prevent UTIs. The aims of this study were to evaluate cranberry-containing products for the prevention of UTI and to examine the factors influencing their effectiveness.


METHODS
MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were systemically searched from inception to November 2011 for randomized controlled trials that compared prevention of UTIs in users of cranberry-containing products vs placebo or nonplacebo controls. There were no restrictions for language, population, or publication year.


RESULTS
Thirteen trials, including 1616 subjects, were identified for qualitative synthesis from 414 potentially relevant references; 10 of these trials, including a total of 1494 subjects, were further analyzed in quantitative synthesis. The random-effects pooled risk ratio (RR) for cranberry users vs nonusers was 0.62 (95% CI, 0.49-0.80), with a moderate degree of heterogeneity (I(2) = 43%) after the exclusion of 1 outlier study. On subgroup analysis, cranberry-containing products seemed to be more effective in several subgroups, including women with recurrent UTIs (RR, 0.53; 95% CI, 0.33-0.83) (I(2) = 0%), female populations (RR, 0.49; 95% CI, 0.34-0.73) (I(2) = 34%), children (RR, 0.33; 95% CI, 0.16-0.69) (I(2) = 0%), cranberry juice drinkers (RR, 0.47; 95% CI, 0.30-0.72) (I(2) = 2%), and subjects using cranberry-containing products more than twice daily (RR, 0.58; 95% CI, 0.40-0.84) (I(2) = 18%).


CONCLUSIONS
Our findings indicate that cranberry-containing products are associated with protective effect against UTIs. However, this result should be interpreted in the context of substantial heterogeneity across trials.
Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Chih-Hung
CH
Wang
Cheng-Chung
CC
Fang
Nai-Chuan
NC
Chen
Sot Shih-Hung
SS
Liu
Ping-Hsun
PH
Yu
Tao-Yu
TY
Wu
Wei-Ting
WT
Chen
Chien-Chang
CC
Lee
Shyr-Chyr
SC
Chen
D001628:Beverages; D002170:Canada / Q000453:epidemiology; D004198:Disease Susceptibility; D005247:Feeding Behavior; D005260:Female; D005387:Finland / Q000453:epidemiology; D005511:Food Handling; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008519:Medicine, Traditional; D016017:Odds Ratio; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D012737:Sex Factors; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014552:Urinary Tract Infections / Q000453:epidemiology* / Q000517:prevention & control*; D029799:Vaccinium macrocarpon