Inappropriateness of randomised trials for complex phenomena
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《英国医生杂志》
EDITOR—Boutron et al misquote a summary point to suggest that all complex procedures are not amenable to randomised investigation. They note that randomisation within a system of procedural excellence (not in 121 centres in 26 countries) can be a useful investigational tool. This certainly is the case; however, one must remember that procedural excellence always remains in evolution.
Wide variations in confidence and success rates illustrate the dynamic and evolving nature of vaginal breech delivery.1 2 All major advances in technique have occurred in Europe—notable were Bracht's and Thiessen's introduction of a one-phase spontaneous birth resulting in the largest published decrease in perinatal breech mortality.3 4 Experienced European centres showing safety in vaginal breech delivery with these techniques were under-represented in the term breech trial, partly because some declined to participate.
In contrast, the term breech trial was based in North America, where the vaginal breech birth rate is a quarter that in Norway or the Netherlands. The protocol superficially outlined a two-phase birth, neglecting techniques that are widespread in Europe and largely responsible for safe success with vaginal breech birth.5 Despite its design by North American experts, and its international vetting (minimally in Norway, Ireland, France, the Netherlands, Austria, and Germany), the protocol represented a simplified and outdated approach, comparatively less safe for achieving a vaginal breech birth rate > 50%. Declaring this standard the best achievable because it was studied in a randomised fashion seriously breaches the limits of evidence based medicine.
Hannah's suggestion that centres with expertise mount their own randomised trial does not acknowledge that these centres have already shown safety through self audit. As Boutron notes, complex procedures must be analysed adequately and mastered before they can be randomised. In its enthusiasm for the methodological gold standard, the term breech trial put the cart before the horse.
Andrew Kotaska, resident
Department of Obstetrics and Gynaecology, University of British Columbia, Women's Hospital, Vancouver, BC, Canada V6H 3V5 Kotaska@bulkley.net
Competing interests: None declared.
References
Diro M, Puangsricharen A, Royer L, O'Sullivan MJ, Burkett G. Singleton term breech deliveries in nulliparous and multiparous women: a 5-year experience at the University of Miami/Jackson Memorial Hospital. Am J Obstet Gynecol 1999;181: 247-52.
Albrechtsen S, Rasmussen S, Reigstad H, Markestad T, Irgens LM, Dalaker K. Evaluation of a protocol for selecting fetuses in breech presentation for vaginal delivery or cesarean section. Am J Obstet Gynecol 1997;177: 586-92.
Bracht E. Zur Behandlung der Steisslage. Zentralblatt Gynaecol 1938;31: 1735-6.
Thiessen P. Die eigene Geburtsleitung bei Beckenendlage und ihr Gegensatz zur Schul- oder Lehrauffassung. Geburtshilfe Frauenheilkd 1964;24: 661-82.
Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet 2000;356: 1375-83.
Wide variations in confidence and success rates illustrate the dynamic and evolving nature of vaginal breech delivery.1 2 All major advances in technique have occurred in Europe—notable were Bracht's and Thiessen's introduction of a one-phase spontaneous birth resulting in the largest published decrease in perinatal breech mortality.3 4 Experienced European centres showing safety in vaginal breech delivery with these techniques were under-represented in the term breech trial, partly because some declined to participate.
In contrast, the term breech trial was based in North America, where the vaginal breech birth rate is a quarter that in Norway or the Netherlands. The protocol superficially outlined a two-phase birth, neglecting techniques that are widespread in Europe and largely responsible for safe success with vaginal breech birth.5 Despite its design by North American experts, and its international vetting (minimally in Norway, Ireland, France, the Netherlands, Austria, and Germany), the protocol represented a simplified and outdated approach, comparatively less safe for achieving a vaginal breech birth rate > 50%. Declaring this standard the best achievable because it was studied in a randomised fashion seriously breaches the limits of evidence based medicine.
Hannah's suggestion that centres with expertise mount their own randomised trial does not acknowledge that these centres have already shown safety through self audit. As Boutron notes, complex procedures must be analysed adequately and mastered before they can be randomised. In its enthusiasm for the methodological gold standard, the term breech trial put the cart before the horse.
Andrew Kotaska, resident
Department of Obstetrics and Gynaecology, University of British Columbia, Women's Hospital, Vancouver, BC, Canada V6H 3V5 Kotaska@bulkley.net
Competing interests: None declared.
References
Diro M, Puangsricharen A, Royer L, O'Sullivan MJ, Burkett G. Singleton term breech deliveries in nulliparous and multiparous women: a 5-year experience at the University of Miami/Jackson Memorial Hospital. Am J Obstet Gynecol 1999;181: 247-52.
Albrechtsen S, Rasmussen S, Reigstad H, Markestad T, Irgens LM, Dalaker K. Evaluation of a protocol for selecting fetuses in breech presentation for vaginal delivery or cesarean section. Am J Obstet Gynecol 1997;177: 586-92.
Bracht E. Zur Behandlung der Steisslage. Zentralblatt Gynaecol 1938;31: 1735-6.
Thiessen P. Die eigene Geburtsleitung bei Beckenendlage und ihr Gegensatz zur Schul- oder Lehrauffassung. Geburtshilfe Frauenheilkd 1964;24: 661-82.
Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet 2000;356: 1375-83.