Paper discussed: J Glavind et al. Elective caesarean section at 38 weeks versus 39 weeks: neonatal and maternal outcomes in a randomised controlled trial. BJOG 2013;120:1123–32.
Date of journal club: 3 July 2013
Number of participants: 12; Number of tweets: 92
|Participants||Uncomplicated singleton pregnancies planned to deliver by elective caesarean section (CS)|
|Intervention||Elective CS scheduled at a gestational age of 38+3 weeks|
|Comparison||Elective CS scheduled at a gestational age of 39+3 weeks|
|Outcomes||Neonatal intensive care unit (NICU) admission <48 hours|
|Study design||Randomised controlled trial (1 : 1)|
Research literacy: was the study sufficiently powered?
This trial showed a non-significant reduction in NICU admission rate from 13.9% to 11.9% in the 39-week group, while all other endpoints favoured the 39-week group as well. The power calculation was based on estimated difference in NICU admission, using the host unit's data.
Power captures whether a statistically nonsignificant difference is due to chance, based on an expected change in effect size for an outcome measure. A change of effect size or outcome measure therefore changes the power. Using estimates for change in effect size based on historical studies (e.g. Tita et al.N Engl J Med 2009, 360: 111–20) suggested that sample size should be larger. Therefore, this study is at risk of being under-powered, resulting in inconclusive results.
Was the primary outcome appropriate?
The primary outcome, NICU admittance, was chosen to assess both risks and advantages with timing of the CS. Because NICU admission is not a direct measure of child condition, an alternative outcome was suggested, e.g. a composite neonatal outcome, with NICU admission as a component of such a composite outcome.
Was the study ethical?
Conducting a trial is ethical when equipoise exists, the uncertainty of what treatment is best for a patient's health. Two types are practiced: (1) clinical equipoise—uncertainty in the physician community, and (2) uncertainty principle—a single physician is uncertain. The question arises if there was equipoise, because other studies had previously reported that CS before 39 weeks of gestation is potentially harmful for neonatal outcome. Despite the evidence in some European countries, a tendency towards earlier CS is present.
Take home message
There was no advantage to perform CS before 39 weeks of gestation. Historical studies have already suggested that elective CS before 39 weeks is associated with potentially harmful effects on neonatal outcome. The current evidence did not support a change in practice.
We thank all participants. A transcript and a list of contributors can be viewed here: http://bit.ly/1aBEVDX.
MAP Bruinooge, FJR Hermans & BWJ Mol
Department of Obstetrics and Gynaecology, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
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