Cranberry Capsules for Reduction of Bacteriuria Plus Pyuria in Nursing Home Women: A Randomized Clinical Trial

Abstract

Background. Bacteriuria plus pyuria is highly prevalent among female nursing home residents. Cranberry capsules are an understudied, non-antimicrobial, prevention strategy in this population. The primary aim was to test the efficacy of two oral cranberry capsules once per day, each capsule containing 36 mg of the active ingredient proanthocyanidin (i.e. 72 mg total, equivalent to 20 ounces of cranberry juice), for reduction of bacteriuria plus pyuria among female nursing home residents. Methods. This was a double-blind, randomized, placebo-controlled efficacy trial of two cranberry capsules with stratification by nursing home. The primary outcome was the presence of bacteriuria (i.e. at least 105 cfu/mL of one or two organisms on urine culture) plus pyuria (i.e. any number of white blood cells on urinalysis) every two months for a total of six assessments over one year of surveillance. Secondary outcomes were symptomatic UTI, death, hospitalization, multi-drug antibiotic resistant organisms, antibiotic prescriptions for suspected UTI, and all antimicrobial prescriptions. Results. Twenty-one CT nursing homes participated in this clinical trial, and 185 women were randomized. The mean age of participants was 86.4 years (± 8.2) and 90.3% were white. Participants had a median of five coexisting conditions and 31.9% had bacteriuria at baseline. Overall adherence to capsule administration was 80.1%. Unadjusted results showed the presence of bacteriuria plus pyuria in 25.5% of the treatment group and 29.5% of the control group. The adjusted GEE model that accounted for missing data and covariates showed no significant difference between the treatment and control groups (29.1% versus 29.0%; OR 1.01, 95% CI 0.61, 1.66; P = 0.984). There were no significant differences in number of symptomatic UTIs, rates of death, hospitalization, multi-drug resistant gram-negative rod bacteriuria, antibiotics administered for suspected UTI, or overall antimicrobial utilization. Conclusion. Despite high adherence to capsule administration and a standardized dose of proanthocyanidin, cranberry capsules did not reduce bacteriuria plus pyuria among older nursing home women. Efficacy of cranberry capsules in other patient populations should be investigated.