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Table 6 Characteristics of included publications

From: A systematic review of non-antibiotic measures for the prevention of urinary tract infections in pregnancy

Author, Year, Country Wing et al., 2008, USA [28]
Design Pilot randomised control trial comparing cranberry juice with placebo.
Participants were divided into three groups and asked to drink 240 ml of either cranberry or placebo juice.
A. cranberry juice three times daily
B. cranberry juice once and placebo twice daily
C. placebo three times daily
Note: High withdrawal led to modification of dose frequency to twice daily in the middle of the trial. Randomisation was stratified by site.
Aim To determine effectiveness of cranberry juice at reducing the frequency of ASB.
Participants 188 pregnant women < 16 weeks gestation
Key findings Results report a 57% reduction in bacteriuria and 41% reduction in all UTIs.
Authors concluded that cranberries provide protection against ASB as well as symptomatic infections.
Limitations Small sample size as it was a pilot.
About 39% participants dropped out due to gastrointestinal issues.
Author, Year, Country Essadi et al., 2010, Libya [29]
Design Randomised control trial comparing cranberry juice to placebo (water).
Participants were divided into two groups and asked to drink 250 ml of cranberry juice or water.
A: cranberry juice four times daily
B: water four times daily
Note: This publication is from a conference poster and full details were not available.
Aim To determine the effectiveness of cranberry juice at reducing the frequency of UTIs.
Participants 760 pregnant women
Key findings Results report that 70.5% of patients who drank cranberry juice showed a significant reduction (p < 0.05) in frequency of UTI compared to 32.16% who drank water.
Of women who developed symptomatic UTI, 4.12% delivered prematurely.
Authors concluded that cranberry juice has a protective effect in UTI prevention.
Limitations There was no blinding as cranberry juice is distinguishable from water.
High withdrawal rate of participants (28%) attributed to gastrointestinal upset.
It is not clear whether authors used intention to treat analysis which may distort results in favour of cranberry juice.
Author, Year, Country Elzayat et al., 2017, Egypt [26]
Design An observational study to determine prevalence of ASB and the risk factors associated with it in pregnancy. Urine specimens were collected and analysed to determine ASB. A survey was conducted using a pre-tested questionnaire to gather data for the associated risk factors.
Aim To determine the prevalence of ASB and identify risk factors associated with it in terms of socioeconomic status or personal hygiene.
Participants 170 pregnant women between the ages of 18–41.
Key findings The prevalence of ASB was 10% (CI 95% 5.93% to 15.53%) in this sample of pregnant women.
There was an association between sexual activity and incidence of ASB and 14% of women with ASB reported sexual activity > twice per week (p = 0.01).
There was also an association between direction of wiping and 15% of women with ASB reported wiping their genitals from back to front (p = 0.03).
No other significant association was found.
Authors recommended educating women on the significance of personal hygiene to prevent UTI during pregnancy.
Limitations This is an observational study and data was collected by questionnaire which is subject to accurate participant recall.
Confidence intervals were not reported for all the categories.
Author, Year, Country Amiri et al., 2009, Iran [25]
Design An observational case-control study. Cases (women with UTI) and controls (no UTI) were matched and compared in terms of difference in genital hygiene or sexual activity. The women were administered a questionnaire by a midwife following which a urine sample was taken for analysis.
Aim To determine association of genital hygiene and sexual activity with the frequency of UTIs in pregnant women.
Participants 250 pregnant women (100 cases and 150 controls)
Key findings The authors investigated multiple factors. Of note is the significant association seen with:
Sexual activity > thrice a week (OR = 5.62 95% CI: 3.10–10.10)
Not voiding the bladder after intercourse (OR = 8.62 95% CI: 6.66–16.66)
Washing genital area from back to front (OR - 2.96 95% CI: 1.66–5.28)
Limitations This was an observational study and data was collected using a questionnaire which is subject to accurate participant recall. Matching of cases and controls is not reported in detail.
Author, Year, Country Baertschi et al., 2003, Switzerland [33]
Design A before and after study testing a bacterial extract’s (OM-8930) efficacy and safety in preventing the incidence of UTIs during pregnancy.
Aim To determine the effect of immunisation on the number of UTI recurrences, the number and duration of antibiotic treatment used and establish the safety of the vaccine (in women or new born).
Participants 62 women 16–28 weeks pregnant
Key findings The extract significantly reduced the recurrence of UTIs from 52.5% to 19.4% (p = 0.002).
Number of people needing antibiotic treatment reduced from 55.7% to 12.9% (p = 0.0002)
Duration of antibiotic treatment reduced from a mean of 3.2 to 2 days (p = 0.0016)
The authors concluded that OM-8930 reduced the number of UTI recurrences but a larger trial was needed to confirm this result.
Limitations The study compares data from the trial to the 6 month period prior to the study instead of comparison with a control group. There is a risk of bias due to this because women’s pregnancy status would likely be different at the two times. Also, The study was a pilot and had a small sample size.
Author, Year, Country Grischke & Ruttgers, 1987, Germany [35]
Design An open comparative randomised trial comparing effectiveness of a vaccine preparation, Solco-Urovac®, to standard antibiotic therapy for prevention of UTIs. The participants were divided into two groups
Group 1: 200 participants given Solco-Urovac® (68 were pregnant)
Group 2: 198 participants given nitrofurantoin or another appropriate antibiotic
Aim To establish the effectiveness of Solco-Urovac® in reducing the frequency of UTIs.
Participants 400 pregnant and non-pregnant women
Key findings There were 28 infections in the trial group and 84 infections in the control group – this was a significant difference (p ≤ 0.001).
Average duration of the infection was significantly longer than in the control group.
No adverse effects were observed in the offspring.
Limitations The study was not conducted exclusively in pregnant women and their proportion in each group is not specified.
Randomisation was not done appropriately as the treating physician may have allocated patients with acute symptoms to the antibiotic group.
Author, Year, Country Ochoa-Brust et al., 2007, Mexico [36]
Design A randomised trial to assess the prophylactic role of ascorbic acid in preventing UTIs during pregnancy. Participants were divided into two groups.
Group A: treatment with ferrous sulphate 200 mg, folic acid 5 mg and ascorbic acid 100 mg daily for 3 months
Group B: treatment with ferrous sulphate 200 mg and folic acid 5 mg daily for 3 months.
Aim To determine the role of ascorbic acid in reducing the frequency of UTIs.
Participants 110 pregnant women, 55 in each group.
Key findings The infection percentage was 12.7% in Group A and 29.1% in Group B (p = 0.03, OR 0.35, CI 95% 0.13–0.91).
The relative risk reduction was 56.5% and absolute risk reduction was 16.3%,
The number needed to treat was 6.
The authors concluded that pregnant women in areas with high rates of antimicrobial resistance should take ascorbic acid during gestation to prevent UTIs.
Limitations Patients were excluded from study if they were not compliant, had serious side effects or if they had a UTI recurrence which may have distorted the results in favour of ascorbic acid.
Author, Year, Country Ordzhonikidze et al., 2009, Russia [38]
Design Two groups of pregnant women were treated with Canephron® N.
Group 1: 160 women with an exacerbation of pyelonephritis were given Canephron® N in combination with standard therapy (antibiotics).
Group 2: 140 women with chronic history of urinary tract disease who were given Canphron® N alone for prevention.
The dose of Canephron® N was two tablets three times a day.
Aim To assess the role of Canephron® N in the management of urinary tract diseases in pregnant women.
Participants 300 pregnant women
Key findings Group 2 seemed to show more favourable results compared to Group 1. The percentage frequency of exacerbation of pyelonephritis was 10–6.25 in Group 1 and 3–2.1 in Group 2.
The authors state in the results section that there was a 1.5-fold decrease in the frequency of infectious complications in the first group and a 1.3-fold decrease in the second group when comparing results to previous years.
Limitations The methods, results and analysis have not been reported clearly.
Canephron® N was not compared to a placebo or to antibiotics.