BMJ  2005;330:95 (8 January), doi:10.1136/bmj.330.7482.95

Letter

Inappropriateness of randomised trials for complex phenomena

Are the results of the term breech trial generalisable?

EDITOR—In the term breech trial planned caesarean section was associated with a lower risk of death and initial serious morbidity, for singleton breech babies at term, compared with planned vaginal birth, although no benefit of planned caesarean was evident at 2 years of age.^{1 2}

Kotaska does not believe that these results are generalisable and thinks that practitioners must have pushed their comfort level for vaginal breech delivery to achieve a vaginal delivery rate of 57%³. However, this rate was for women having a trial of labour and is similar to rates found in published reports.³

Kotaska also criticises the selection criteria and the intrapartum management of women planning a vaginal breech delivery in the trial, despite the fact that the protocol was developed at a consensus workshop by a group of obstetricians who were recognised in their communities as expert at vaginal breech delivery, and was then vetted by experienced obstetricians worldwide.⁴

We agree that operators' skill is crucially important in evaluating surgical interventions but continue to believe that randomised controlled trials provide the best evidence as to whether such procedures cause more good than harm.⁵ We sympathise with practitioners who do not believe that the results of the term breech trial apply to them. No one was more disappointed with the findings of the trial than the participating clinicians themselves who believed in the safety of vaginal breech delivery but were willing to put their vaginal breech delivery skills to the test.

University of Toronto Maternal Infant and Reproductive Health Research Unit, Centre for Research in Women's Health, Suite 751,790 Bay Street, Toronto, ON, Canada M6G 1N8 Mary.Hannah{at}sw.ca

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Competing interests: None declared.

For the Term Breech Trial Steering Committee and Collaborative Group

References

1. Hannah ME, Hannah WJ, Hewson S, Hodnett E, Saigal S, Willan A, for the Term Breech Trial Collaborative Group. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Lancet 2000;356: 1375-83.[CrossRef][ISI][Medline]
2. Whyte H, Hannah ME, Saigal S, Hannah WJ, Hewson S, Amankwah K, et al. Outcomes of children at 2 years after planned cesarean birth vs planned vaginal birth for breech presentation at term: the international randomized term breech trial. Am J Obstet Gynecol 2004;191: 864-71.[CrossRef][Medline]
3. Kotaska A. Inappropriate use of randomised trials to evaluate complex phenomena: case study of vaginal breech delivery. BMJ 2004;329: 1039-42. (30 October.)[Free Full Text]
4. Hannah WJ, Allardice J, Amankwah K, Baskett T, Cheng M, Fallis B, et al. The Canadian consensus on breech management at term. Journal of the Society of Obstetricians and Gynaecologists of Canada 1994;4: 1839-58.
5. Su M, McLeod L, Ross S, Willan A, Hannah WJ, Hutton E, et al, for the Term Breech Trial Collaborative Group. Factors associated with adverse perinatal outcome in the Term Breech Trial. Am J Obstet Gynecol 2003;189: 740-5.[Medline]

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Inappropriate use of randomised trials to evaluate complex phenomena: case study of vaginal breech delivery

Andrew Kotaska
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