Pilot Study to Evaluate Compliance and Tolerability of Cranberry Capsules in Pregnancy for the Prevention of Asymptomatic Bacteriuria

Abstract

Objectives: To evaluate the compliance with and tolerability of daily cranberry capsule ingestion for asymptomatic bacteriuria (ASB) prevention in pregnancy.

Design: A total of 49 pregnant women from two sites were randomly assigned to cranberry or matching placebo, two doses daily, at gestational ages less than 16 weeks. Patients were followed monthly for urinary tract infection until delivery. Up to seven monthly visits were scheduled for each patient. Delivery data were evaluated.

Results: Of 38 evaluable patients, the mean compliance rate over the study period was 82% (range, 20%-100%). This compliance rate and the 74% of patients achieving good (≥75%) compliance were similar between those who received cranberry capsules and placebo. Compliance evaluation revealed that most patients stopped capsule consumption after 34-38 weeks of participation. Multivariate logistic regression and longitudinal analysis showed a significant interaction time effect with cranberry treatment. However, cranberry consumption was not a significant predictor of gastrointestinal intolerance or study withdrawal. Although 30% of patients withdrew for various reasons, only 1 withdrew because of intolerance to the cranberry capsules. Loss to follow-up was mostly due to provider change (9 of 49 [18%]) and therapy disinterest (4 of 49 [8%]). Seven cases of ASB occurred in 5 patients: 2 of 24 (8%) in the cranberry group and 3 of 25 (12%) in the placebo group. No cases of cystitis or pyelonephritis were observed.

Conclusion: One third of pregnant women could not complete the study protocol for various reasons. Compliance with and tolerability of cranberry capsule ingestion appear good; these capsules provide a potentially effective means to prevent ASB in pregnancy. Further studies with large samples are necessary to confirm the findings.

FIG. 1.

Patient population. “Screened” refers to total number of patients screened for study. “Not eligible” refers to number of patients not meeting criteria for study. “Eligible” refers to number of patients meeting criteria for study. “Nonparticipants” refers to women who were eligible for study but did not participate (this includes those who declined and those who disliked cranberries). “Subjects enrolled” refers to the total number of participants in study. “Cranberry” refers to number of participants assigned to cranberry capsules. “Placebo” refers to number of participants assigned to placebo. LBMMC and LB, Long Beach Memorial Medical Center; UCIMC and UCI, University of California Irvine Medical Center.

FIG. 2.

Mean compliance rate during study period.