How should randomised trials including multiple pregnancies be analysed?

Gates, Simon; Brocklehurst, Peter

doi:10.1111/j.1471-0528.2004.00059.x

Cited by 107 publications

(94 citation statements)

References 14 publications

(10 reference statements)

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“…In the analysis of neonatal outcomes, neonates from multiple births were treated as independent, but the eff ect of adjusting for potential clustering was also assessed. 14 The focus of the primary analysis was the main eff ects of the fi ve intervention pairs analysed separately. Pairwise interactions were planned if the analyses showed any statistically signifi cant main eff ects for the primary outcome only.…”

Section: Discussionmentioning

confidence: 99%

Caesarean section surgical techniques (CORONIS): a fractional, factorial, unmasked, randomised controlled trial

Ábalos¹,

et al. 2013

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SummaryBackground Variations exist in the surgical techniques used for caesarean section and many have not been rigorously assessed in randomised controlled trials. We aimed to assess whether any surgical techniques were associated with improved outcomes for women and babies.Methods CORONIS was a pragmatic international 2×2×2×2×2 non-regular fractional, factorial, unmasked, randomised controlled trial that examined fi ve elements of the caesarean section technique in intervention pairs. CORONIS was undertaken at 19 sites in Argentina, Chile, Ghana, India, Kenya, Pakistan, and Sudan. Each site was assigned to three of the fi ve intervention pairs: blunt versus sharp abdominal entry; exteriorisation of the uterus for repair versus intraabdominal repair; single-layer versus double-layer closure of the uterus; closure versus non-closure of the peritoneum (pelvic and parietal); and chromic catgut versus polyglactin-910 for uterine repair. Pregnant women were eligible if they were to undergo their fi rst or second caesarean section through a planned transverse abdominal incision. Women were randomly assigned by a secure web-based number allocation system to one intervention from each of the three assigned pairs. All investigators, surgeons, and participants were unmasked to treatment allocation. The primary outcome was the composite of death, maternal infectious morbidity, further operative procedures, or blood transfusion (>1 unit) up to the 6-week follow-up visit. Women were analysed in the groups into which they were allocated. The CORONIS Trial is registered with Current Controlled Trials: ISRCTN31089967. Interpretation These fi ndings suggest that any of these surgical techniques is acceptable. However, longer-term follow-up is needed to assess whether the absence of evidence of short-term eff ects will translate into an absence of long-term eff ects.Funding UK Medical Research Council and WHO.

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Section: Discussionmentioning

confidence: 99%

Caesarean section surgical techniques (CORONIS): a fractional, factorial, unmasked, randomised controlled trial

Ábalos¹,

et al. 2013

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“…Multiple births are an important subgroup to consider in such trials, since multiples account for around a quarter of all preterm births and half of all twins are born preterm 1. Including multiple births in a trial can be challenging due to the correlation between outcomes of infants from the same birth that results from shared environmental and genetic factors 2 3. Correlated or clustered data are common in health research and methods for analysing these types of data are widely discussed 4–8.…”

Section: Introductionmentioning

confidence: 99%

Accounting for multiple births in randomised trials: a systematic review

Yelland

Sullivan

Makrides

2014

Arch Dis Child Fetal Neonatal Ed

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“…We also conducted a sensitivity analysis including multiple births, with clustering of outcomes accounted for using an approach previously published. 87 This adapts methodology previously created for use with cluster RCTs, assuming that each woman is regarded as the 'cluster' and her number of offspring as the cluster size. A chi-squared test was used to compare the total number of women or their infants who had at least one AE or serious adverse event (SAE).…”

Section: Fetal and Maternal Birth Outcomesmentioning

confidence: 99%

The London Exercise And Pregnant smokers (LEAP) trial: a randomised controlled trial of physical activity for smoking cessation in pregnancy with an economic evaluation

Ussher

Lewis

Aveyard

et al. 2015

Health Technol Assess

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BackgroundSmoking during pregnancy is the main preventable cause of poor birth outcomes. Improved methods are needed to help women to stop smoking during pregnancy. Pregnancy provides a compelling rationale for physical activity (PA) interventions as cessation medication is contraindicated or ineffective, and an effective PA intervention could be highly cost-effective.ObjectiveTo examine the effectiveness and cost-effectiveness of a PA intervention plus standard behavioural support for smoking cessation relative to behavioural support alone for achieving smoking cessation at the end of pregnancy.DesignMulticentre, two-group, pragmatic randomised controlled trial and economic evaluation with follow-up at the end of pregnancy and 6 months postnatally. Randomisation was stratified by centre and a computer-generated sequence was used to allocate participants using a 1 : 1 ratio.Setting13 hospitals offering antenatal care in the UK.ParticipantsWomen between 10 and 24 weeks’ gestation smoking five or more cigarettes a day before pregnancy and one or more during pregnancy.InterventionsParticipants were randomised to behavioural support for smoking cessation (control) or behavioural support plus a PA intervention consisting of supervised treadmill exercise plus PA consultations. Neither participants nor researchers were blinded to treatment allocation.Main outcome measuresThe primary outcome was self-reported, continuous smoking abstinence between a quit date and end of pregnancy, validated by expired carbon monoxide and/or salivary cotinine. Secondary outcomes were maternal weight, depression, birth outcomes, withdrawal symptoms and urges to smoke. The economic evaluation investigated the costs of the PA intervention compared with the control intervention.ResultsIn total, 789 women were randomised (n = 394 PA,n = 395 control). Four were excluded post randomisation (two had been enrolled twice in sequential pregnancies and two were ineligible and randomised erroneously). The intention-to-treat analysis comprised 785 participants (n = 392 PA,n = 393 control). There was no significant difference in the rate of abstinence at the end of pregnancy between the PA group (7.7%) and the control group (6.4%) [odds ratio for PA group abstinence 1.21, 95% confidence interval (CI) 0.70 to 2.10]. For the PA group compared with the control group, there was a 33% (95% CI 14% to 56%), 28% (95% CI 7% to 52%) and 36% (95% CI 12% to 65%) significantly greater increase in self-reported minutes of moderate- and vigorous-intensity PA from baseline to 1 week, 4 weeks and 6 weeks respectively. Accelerometer data showed that there was no significant difference in PA levels between the groups. There were no significant differences between the groups for change in maternal weight, depression, withdrawal symptoms or urges to smoke. Adverse events and birth outcomes were similar between the groups except for there being significantly more caesarean births in the control group than in the PA group (28.7% vs. 21.3%;p < 0.023). The PA intervention was less costly than the control intervention by £35 per participant. This was mainly attributable to increased health-care usage in the control group. However, there was considerable statistical uncertainty around this estimate.ConclusionsDuring pregnancy, offering an intervention combining supervised exercise and PA counselling does not add to the effectiveness of behavioural support for smoking cessation. Only 10% of participants had PA levels accessed by accelerometer and it is, therefore, unclear whether or not the lack of an effect on the primary outcome is the result of insufficient increases in PA. Research is needed to identify the smoking populations most suitable for PA interventions and methods for increasing PA adherence.Trial registrationCurrent Controlled Trials ISRCTN48600346.FundingThis project was funded by the NIHR Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 19, No. 84. See the NIHR Journals Library website for further project information.

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How should randomised trials including multiple pregnancies be analysed?

Cited by 107 publications

References 14 publications

Caesarean section surgical techniques (CORONIS): a fractional, factorial, unmasked, randomised controlled trial

Caesarean section surgical techniques (CORONIS): a fractional, factorial, unmasked, randomised controlled trial

Accounting for multiple births in randomised trials: a systematic review

The London Exercise And Pregnant smokers (LEAP) trial: a randomised controlled trial of physical activity for smoking cessation in pregnancy with an economic evaluation

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