Pill that can prevent blood clots after surgery

A daily pill may save the lives of thousands of people who die each year in hospitals from blood clots after surgery, reported The Daily Telegraph. Blood clots “kill 25,000 people a year in English hospitals, more than the number of people who die from breast cancer, Aids or road traffic accidents” the newspaper stated. A recent government report suggested that “every hospital patient should have their own risk assessment for VTE (blood clots) that will improve patient safety and help save thousands of lives each year”.

The story is based on a large randomised controlled trial in which more than 1,100 people were given this pill after undergoing total hip replacement and compared with 1,100 who were treated as usual (with daily heparin injections) after their surgery. The study shows that the new treatment is no worse than usual care, with a similar profile of side effects and there could be benefits to taking a pill instead of an injection.

Where did the story come from?

Bengt Eriksson and colleagues from the Sahlgrenska University Hospital in Gothenburg, Sweden conducted this research. The study was funded by Boehringer Ingelheim, the manufacturers of the drug being studied and was published in the peer-reviewed medical journal the Lancet.

What kind of scientific study was this?

The study was a double-blind randomised controlled trial. The trial used a particular design that allows researchers to see whether a new treatment is ‘no worse than’ another treatment.

The researchers chose at random 3,494 people who were scheduled to undergo a total hip replacement. One group was given the new treatment dabigatran etexilate (one of two doses) while the other underwent the usual treatment with an injection of heparin. All participants were at least 18 years old and weighed at least 40kg (6 stone 4lbs, 88lbs). The participants were drawn from 115 medical centres across Europe, Australia, and South Africa.

The researchers compared the effects of the treatments on ‘venous thromboembolic events’ (blood clots) and death due to any cause. The researchers also assessed the safety of the new treatment by examining how many people experienced bleeding events during treatment.

What were the results of the study?

The researchers found that similar outcomes for patients given either one of the two doses (200mg or 150mg) of dabigatran etexilate or daily injections of heparin after total hip replacement. They were particularly interested in a combined measure of the patient’s experience of blood clots in the veins and death from any cause. They found that 6.7% of people given heparin experienced this compared with 6.0% of people in the high-dose dabigatran etexilate group and 8.6% of people in the low dose group.

What interpretations did the researchers draw from these results?

The researchers found that dabigatran etexilate tablets were as effective as injections of heparin for preventing blood clots and death after hip replacement surgery.

What does the NHS Knowledge Service make of this study?

This is a large, well-conducted randomised controlled trial that suggests that dabigatran etexilate tablets may have a potential role in the future for the preventative treatment of blood clots after surgery. Points to bear in mind when interpreting this study:

• The researchers acknowledge one potential weakness of their study, the fact that 24% of people who received treatment were not available for measurements at the end of the study. However, they performed certain statistical tests that suggested that these people would not have made much of a difference to their conclusions about the two treatments. 
• The optimum dose of dabigatran etexilate has not been established, and the researchers say that findings from a large study that is currently underway will help to establish this.
• In this type of trial, researchers must choose a ‘clinically significant’ cut off by which they can compare treatments. In this study, the researchers decided that as long as dabigatran etexilate did not result in 7.7% more events (blood clots or death from any cause), it could be considered as effective as heparin. Other researchers may have different opinions on what they consider a clinically relevant difference between these treatments
• This study does not suggest that the current practice of giving heparin injections to patients after hip surgery is inferior to these new tablets; this has been effective medical practice for many years now. The report in the newspaper that ‘a pill taken once a day could save the lives of thousands of people who die in English hospitals every year from blood clots’ is slightly misleading. 
• The newspaper also mentioned that it is a ‘daily pill’. This should also not be interpreted to mean that this pill is an alternative treatment for long-term use. Patients requiring longer term treatment to prevent blood clots (after the initial four-week post-surgery period) would normally be started and monitored on warfarin tablets.
• Further studies will also be needed using these tablets in other contexts besides hip surgery patients, for example in non-surgical patients with other risk factors who present as emergency cases with deep vein blood clots.

Tablet formulations of anti-coagulants are certainly an attractive option. Such tablets will allow people to have greater control over aspects of their own post-operative care.