Background
Methods
Sources and searching
Review Selection
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Assess retrieved titles and abstracts for relevance and duplication.
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Select those you wish to retrieve and appraise further.
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Obtain full text copies of these potentially eligible reviews.
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Assess these reviews for relevance and quality; ideally, using independent assessment by at least two members of the review team. This reduces bias in review selection and allows for appropriate discussion should uncertainty arise.
Quality Assessment of Reviews
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▪ The extent of searching undertaken: Are the databases searched, years searched and restrictions applied in the original review clearly described? Information on the extent of searching should be clearly provided, to allow for a comprehensive assessment of the scope of the review.
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▪ Description of review selection and inclusion criteria: Do the authors of the original review provide details of study selection and eligibility criteria and what are these details? This information should be clearly reported in the systematic review of reviews.
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▪ Assessment of publication bias: Did the authors of the original review seek additional information from authors of the studies they included? Are there any details of statistical tests (such as funnel plot analysis) to assess for publication bias?
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▪ Assessment of heterogeneity: Did the authors of the original review discuss or provide details of any tests of heterogeneity? In the presence of significant heterogeneity, were statistical tests used to address this?
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▪ Comparability of included reviews: Are the reviews comparable in terms of eligibility criteria, study characteristics and primary outcome of interest? For example, in our review of reviews on fetal fibronectin and transvaginal cervical ultrasound for predicting preterm birth, [8] we included reviews that had incorporated studies among women who were both symptomatic and asymptomatic for preterm birth. As a means of addressing comparability of the included reviews, we provided details of the number of women in each group separately and reported the results for each group separately, where applicable.
Presentation of Results
Review Year | Aim (participants) | Search strategy | No. of studies included | Total no. of participants | Timing of preventative strategy |
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King & Flenady 2002 | To assess the effects of prophylactic antibiotics on preterm labour (women symptomatic for preterm labour) | Cochrane Pregnancy & Childbirth Group (May 2002) Search terms provided. No language restrictions | 11 | 7428 (6295 enrolled in one trial) | Mean gestational age at entry to all trials 30-32 weeks (but varied across studies) |
Simcox et al 2007 | To determine if antibiotics reduce the risk of preterm birth (asymptomatic women at risk, e.g. previous preterm birth or positive fibronectin status) | Cochrane Pregnancy & Childbirth Group (2005) Search terms provided. English language publications. | 17 | 1291 | 12-28 weeks across studies |
Review | Tocolytic agent | Birth >48 hrs (95% CI) | Birth >7 days (95% CI) | Birth >34 weeks (95% CI) | Birth >37 weeks (95% CI) |
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King 1988 | Betamimetics compared with placebo or no treatment | 12 trials OR 0.59, (0.42-0.83) Significant | - | - | 8 trials OR 0.71 (0.53-0.96) Significant |
Coomarasamy et al 2002 | Atosiban V placebo (2 trials) Atosiban V beta-agonist (4 trials) | 2 trials RR 1.13, (1.02-1.26) Significant 4 trials RR 1.07 (0.98-1.17) Not significant | - 3 trials RR 1.25 (1.09-1.44) Significant | - | - |
Crowther et al 2002 | Magnesium sulphate V placebo/no treatment or other tocolytic agent | 11 trials RR 0.85, (0.58-1.25) Not significant | - | No difference reported | No difference reported |
King et al 2003 | Calcium channel blockers V any other tocolytic agent | - | RR 0.76, (0.60-0.97) Significant | RR 0.83, (0.69-0.99) Significant | RR 0.95, (0.83-1.09) Not significant |
Anotayanonth et al 2004 | Betamimetics V Placebo | 11 trials RR 0.63, (0.53-0.75) Significant | 11 trials RR 0.78, (0.68-0.90) Significant | - | 11 trials RR 0.95, (0.88-1.03) Not significant |
King et al 2005 | COX inhibitor V Placebo COX inhibitor V any other tocolytic | 2 trials RR 0.20, CI 0.03-1.28 4 trials RR 0.59, CI 0.34-1.02 | 2 trials RR 0.41, CI 0.10-1.66 | - | 3 trials RR 0.21, CI 0.07-0.62 3 trials RR 0.53, CI 0.31-0.94 |
Whitworth & Quenby 2008 | Oral betamimetic V placebo | - | - | - | RR 1.07, (0.14-8.09) Not significant |