Does tranexamic acid prevent postpartum haemorrhage? A systematic review of randomised controlled trials

Clinical Trials Unit, London School of Hygiene & Tropical Medicine, London, UK.

Bjog : an International Journal of Obstetrics and Gynaecology. 2016;123((11):):1745-52.

Clinical Commentary

What is known?

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality worldwide with about 50,000 deaths each year. In those women who survive PPH, hysterectomy is sometimes necessary to stop the haemorrhage, depriving many women of their ability to bear additional children. Tranexamic acid (TXA) reduces bleeding by inhibiting fibrinolysis. TXA is an inexpensive, widely available drug that has been proven to reduce bleeding in surgery and reduce the risk of death in bleeding trauma patients. TXA given at delivery could potentially prevent severe postpartum bleeding.

What did this paper set out to examine?

The authors conducted a systematic review of randomised controlled trials (RCTs) to assess the effects of TXA on the risk of PPH as well as other clinically relevant outcomes. They searched MEDLINE, CENTRAL, EMBASE, PubMed, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform electronic databases for reviews published as of May 2015. Selection criteria included RCTs comparing TXA with no TXA or placebo in women giving birth vaginally or by caesarean section (CS).

What did they show?

The authors found 31 reports describing 26 trials involving 4191 women published between 2001 and 2015. Eight reports contained identical or similar data and there were important clinical inconsistencies in several trials. Two trials did not have ethics committee approval and meta-analysis showed that randomization was inadequate in many trials. The median sample size was 120 patients (74-740). All but one were single centre trials. Trials were conducted in China (3), Egypt (2), India (9), Iran (5), Malaysia (1), Pakistan (2), Turkey (3) and Ukraine (1). Twenty-two trials focused on the effects of TXA on women giving birth by CS and four in women delivering vaginally.

TXA was given within 30 minutes prior to incision in all of the CS trials except one (given at delivery of anterior shoulder). TXA was given at delivery of anterior shoulder in 3 and at delivery of placenta in the remaining vaginal births. The TXA dose ranged from 0.5 g to 1 g. Women receiving TXA were compared to those given placebo in 13 reports and with those in a no-TXA group in the remaining 13 trials.

The number of patients assigned to each group was not reported in one trial, rendering the data unusable. Frequency of PPH was reported in 13 of the trials (50%), blood loss in 24 (92%), thromboembolic events in 16 (62%), death in six (23%), surgical intervention in five (19%) and transfusion of blood products in 10 (38%). No trial reported on maternal well-being or quality of life. A major problem when comparing these studies is that even the definition of what constitutes PPH varied; four trials classified PPH as blood loss = 1000 mL after CS and = 500 mL after vaginal delivery. The remaining trials used other, lower thresholds such as = 500 mL after CS and = 400 mL after vaginal delivery.

Because of the authors’ concerns about the quality of the trials and data reliability, they chose not to perform a meta-analysis. They instead calculated effect estimates and 95% CI’s were presented as Forest plots. They concluded that, in all trials, fewer women in the TXA group developed PPH than in the control group. Additionally, from the data of the trials where blood loss was evaluated, the effect estimates were consistent with less blood loss in the TXA group; the difference was statistically significant in all but one trial. In the trials detailing blood product transfusion data, where products were transfused (7), fewer women in the TXA group received a blood transfusion than in the control group. In studies reporting adverse outcomes, there were no deaths, surgical interventions, myocardial infarctions, strokes or pulmonary embolisms.

What are the implications for practice and for future work?

This publication provided valuable data in its description of the scale and nature of deficiencies in the studies evaluating the effect of TXA in preventing PPH. Unless the problems with these studies are brought to the attention of the maternal fetal medicine and transfusion medicine leaders, treatment decisions may be based on unsound evidence putting women at risk. The information provided by the authors should serve to guide future trial developers such that conclusions are based on the highest quality research possible.

Based on the studies reviewed by the authors, it is clear that large, multicentre randomized control trials with clinically relevant endpoints must be developed before widespread clinical guidelines endorsing TXA in preventing PPH are implemented. It should be noted that the data from the WOMAN trial was not available at the time of this study.

References

Adult Antifibrinolytic Agents/*administration & dosage Delivery, Obstetric/*adverse effects Female Humans Parturition/*drug effects Postpartum Hemorrhage/etiology/*prevention & control Pregnancy Randomized Controlled Trials as Topic Tranexamic Acid/*administration & dosage Treatment Outcome Postpartum haemorrhage systematic review tranexamic acid
Abstract
BACKGROUND Postpartum haemorrhage is the leading cause of maternal mortality. Tranexamic acid (TXA) reduces surgical haemorrhage and the risk of death in bleeding trauma patients. OBJECTIVES To assess the effects of TXA on risk of postpartum haemorrhage and other clinically relevant outcomes. SEARCH STRATEGY We searched the MEDLINE, CENTRAL, EMBASE, PubMed, ClinicalTrials.gov and WHO ICTRP electronic databases to May 2015. SELECTION CRITERIA Randomised controlled trials comparing TXA with no TXA or placebo in women giving birth vaginally or by caesarean section. DATA COLLECTION AND ANALYSIS Two authors extracted data and assessed the risk of bias for each trial. Because of data concerns we did not conduct a meta-analysis. MAIN RESULTS We found 26 trials including a total of 4191 women. Examination of the trial reports raised concerns about the quality of the data. Eight trial reports contained identical or similar text and there were important data inconsistencies in several trials. Two trials did not have ethics committee approval. Meta-analysis of baseline variables suggested that randomisation was inadequate in many trials. CONCLUSIONS There is no reliable evidence that TXA prevents postpartum haemorrhage during childbirth. Many of the trials conducted to date are small, low quality and contain serious flaws. TWEETABLE ABSTRACT No evidence that TXA prevents postpartum haemorrhage. Existing trials are unreliable, with serious flaws.
Study details
Study Design : Systematic Review
Language : English
Additional Material : Commentary in: Bjog. 2017;124(6)982. DOI: 10.1111/1471-0528.14421
Credits : Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine