Uterotonic drugs to prevent postpartum haemorrhage: a network meta-analysis.

BACKGROUND

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality worldwide. Prophylactic uterotonic drugs can reduce blood loss and are routinely recommended. There are several uterotonic drugs for preventing PPH, but it is still debatable which drug or combination of drugs is the most effective.

OBJECTIVES

To identify the most effective and cost-effective uterotonic drug(s) to prevent PPH, and generate a ranking according to their effectiveness and side-effect profile.

METHODS

The Cochrane Pregnancy and Childbirth's Trials Register (1 June 2015), ClinicalTrials.gov and the World Health Organization (WHO)'s International Clinical Trials Registry Platform (ICTRP) were searched for unpublished trial reports (30 June 2015). In addition, reference lists of retrieved studies (updated October 2017) were searched for randomised trials evaluating uterotonic drugs for preventing PPH. The study estimated relative effects and rankings for preventing PPH, defined as blood loss of ≥ 500 ml and ≥ 1000 ml. Pairwise meta-analyses and network meta-analysis were performed to determine the relative effects and rankings of all available drugs and combinations thereof [ergometrine, misoprostol (Cytotec

RESULTS

From 137 randomised trials and 87,466 women, ergometrine plus oxytocin, carbetocin and misoprostol plus oxytocin were found to reduce the risk of PPH blood loss of ≥ 500 ml compared with the standard drug, oxytocin [ergometrine plus oxytocin: risk ratio (RR) 0.69, 95% confidence interval (CI) 0.57 to 0.83; carbetocin: RR 0.72, 95% CI 0.52 to 1.00; misoprostol plus oxytocin: RR 0.73, 95% CI 0.6 to 0.9]. Each of these three strategies had 100% cumulative probability of being ranked first, second or third most effective. Oxytocin was ranked fourth, with an almost 0% cumulative probability of being ranked in the top three. Similar rankings were noted for the reduction of PPH blood loss of ≥ 1000 ml (ergometrine plus oxytocin: RR 0.77, 95% CI 0.61 to 0.95; carbetocin: RR 0.70, 95% CI 0.38 to 1.28; misoprostol plus oxytocin: RR 0.90, 95% CI 0.72 to 1.14), and most secondary outcomes. Ergometrine plus oxytocin and misoprostol plus oxytocin had the poorest ranking for side effects. Carbetocin had a favourable side-effect profile, which was similar to oxytocin. However, the analysis was restricted to high-quality studies, carbetocin lost its ranking and was comparable to oxytocin. The relative cost-effectiveness of the alternative strategies is inconclusive, and the results are affected by both the uncertainty and inconsistency in the data reported on adverse events. For vaginal delivery, when assuming no adverse events, ergometrine plus oxytocin is less costly and more effective than all strategies except carbetocin. The strategy of carbetocin is both more effective and more costly than all other strategies. When taking adverse events into consideration, all prevention strategies, except oxytocin, are more costly and less effective than carbetocin. For delivery by caesarean section, with and without adverse events, the relative cost-effectiveness is different, again because of the uncertainty in the available data.

LIMITATIONS

There was considerable uncertainty in findings within the planned subgroup analyses, and subgroup effects cannot be ruled out.

CONCLUSIONS

Ergometrine plus oxytocin, carbetocin and misoprostol plus oxytocin are more effective uterotonic drug strategies for preventing PPH than the current standard, oxytocin. Ergometrine plus oxytocin and misoprostol plus oxytocin cause significant side effects. Carbetocin has a favourable side-effect profile, which was similar to oxytocin. However, most carbetocin trials are small and of poor quality. There is a need for a large high-quality trial comparing carbetocin with oxytocin; such a trial is currently being conducted by the WHO. The relative cost-effectiveness is inconclusive, and results are affected by uncertainty and inconsistency in adverse events data.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015020005; Cochrane Pregnancy and Childbirth Group (substudy) reference number 0871; PROSPERO-Cochrane (substudy) reference number CRD42015026568; and sponsor reference number ERN_13-1414 (University of Birmingham, Birmingham, UK).

FUNDING

Funding for this study was provided by the National Institute for Health Research Health Technology Assessment programme in a research award to the University of Birmingham and supported by the UK charity Ammalife (UK-registered charity 1120236). The funders of the study had no role in study design, data collection, data synthesis, interpretation or writing of the report.

Postpartum haemorrhage (PPH) is the most common reason why mothers die in childbirth worldwide. Although most healthy women can cope well with blood loss after birth, some do not, and this can pose a serious risk to their health and even life. To reduce blood loss after birth, the routine administration of a drug to contract the uterus (uterotonic) has become standard practice across the world. This research seeks to identify which is the most effective and cost-effective drug. Different drugs have been used for reducing the occurrence of PPH. They include oxytocin, misoprostol, ergometrine, carbetocin, and combinations of these drugs, each with different effectiveness and side effects. The study synthesised the available evidence to compare all of these drugs and combinations thereof. After putting the results of all available comparisons together in a network, a ranking among them was calculated, and provided robust effectiveness and side-effect profiles for each drug and their associated costs. The study included 137 randomised trials, involving a total of 87,466 women. The results suggested that ergometrine plus oxytocin, carbetocin and misoprostol plus oxytocin are the most effective strategies for preventing PPH and are more effective than the currently recommended drug, oxytocin. Each of these three strategies had almost 100% probability of being ranked first, second or third most effective. Oxytocin was ranked fourth with an almost 0% probability of being ranked in the top three. Ergometrine plus oxytocin and misoprostol plus oxytocin were the worst drug combinations for side effects, with carbetocin having the most favourable side-effect profile. Carbetocin could prevent approximately one further event of PPH out of three in comparison with oxytocin. However, existing carbetocin studies were small and of poor quality. There is need for a large high-quality study comparing carbetocin with the current standard treatment of oxytocin for the prevention of PPH. The cost analyses of the alternative drug strategies remain inconclusive.

Déclaration de conflit d'intérêts

Ioannis Gallos, Metin Gülmezoglu, Justus Hofmeyr and Arri Coomarasamy have been involved in one or more previous or ongoing trials related to the use of uterotonics for the prevention of postpartum haemorrhage that were considered for inclusion in this review. Ferring Pharmaceuticals (Saint-Prex, Switzerland) and Novartis Pharmaceuticals UK Ltd (Surrey, UK) have supplied carbetocin and oxytocin to these studies. Ioannis Gallos, Metin Gülmezoglu, Justus Hofmeyr and Arri Coomarasamy have not participated in decisions regarding inclusion of these trials in this review or any tasks related to them such as data extraction or quality assessment. Arri Coomarasamy is involved in a World Health Organization-sponsored randomised controlled trial of carbetocin versus oxytocin, supported by Merck for Mothers (Merck & Co., Inc., Kenilworth, NJ, USA). Metin Gülmezoglu was involved in a large multicentre trial included in the review as part of the central co-ordination unit. As part of the central co-ordination unit, he is also involved in an ongoing World Health Organization-sponsored randomised controlled trial of carbetocin versus oxytocin supported by Merck for Mothers. Abi Merriel is part-funded by Ammalife (a UK-registered charity 1120236) and the Birmingham Women’s NHS Foundation Trust. Harry Gee and Arri Coomarasamy are trustees of Ammalife. Jonathan Deeks is a member of the Health Technology Assessment (HTA) Commissioning Board and the HTA Efficient Study and Designs Board.