This is a plain English summary of an original research article
This Cochrane systematic review found that two new types of drugs taken by mouth for deep vein thrombosis were as effective as standard treatment, which most commonly involves treatment by injection followed by warfarin tablets for at least three months. The new drugs have the advantage that they do not require monitoring or dose changes and were associated with a lower risk of bleeding.
This high quality review was based on evidence from 11 good quality trials and can be considered reliable. This review did not look at overall cost or cost-effectiveness. NICE has conducted some assessments of individual drugs and is conducting further assessments. Each assessment has a costing tool or statement that can be used by clinicians and commissioners weighing up the benefits and costs of potential changes to current treatment pathways (see Bibliography below for links).
Why was this study needed?
Deep vein thrombosis (DVT) describes a blood clot that has formed in the deep veins of the legs or pelvis, that is, not the ones you can see near the surface of the skin. It is relatively common and affects about one in a 1,000 people in the UK each year. There is a risk the clot could move and travel to one of the lung arteries causing a life threatening condition called pulmonary embolism. Pulmonary embolism is estimated to affect 3 to 4 per 10,000 people.
DVT is usually treated first of all by injections of a drug called heparin, followed by an anti-clotting drug taken by mouth, mostly commonly warfarin. But warfarin has several drawbacks. It interacts with other drugs and needs frequent monitoring and dose control to ensure the right balance between clotting and bleeding risk is achieved.
NICE has carried out individual assessments for some of the new drugs that act slightly differently to warfarin. This Cochrane systematic review was conducted to summarise all the available evidence on the effectiveness and safety for the two new types of drugs for people with or at risk of DVT.
What did this study do?
The review searched for published and unpublished randomised controlled trials where one of the two new types of oral anti-clotting drug had been used. These two types are called direct thrombin inhibitors (dabigatran, ximelagatran) and factor Xa inhibitors (rivaroxaban, apixaban and edoxaban).
These drugs were compared with the standard treatments of heparin injections, warfarin or one of the similar drugs. They identified 11 trials including 27,945 people. There were two dabigatran trials, one ximelagatran, four rivaroxaban, two apixaban, and two edoxaban trials. All included studies were rated as high quality. The assessors in 10 of the trials were not aware of which treatment had been given. Six studies were not blinded as the comparison treatment was given by an injection. The results were pooled using meta-analyses where possible to give an overall result.
As there were no trials directly comparing the new drugs with each other this review cannot help in the decision about which drug to prescribe.
What did it find?
- There was no difference in risk of recurrent DVT in those using direct thrombin inhibitors compared with standard treatment (odds ratio [OR] 1.08, 95% confidence interval [CI] 0.74 to 1.58). But factor Xa inhibitors were associated with a significantly reduced risk of recurrent DVT compared with standard treatment (OR 0.75, 95% CI 0.57 to 0.98). However this association was weak and dependent on the results of one study.
- There was no difference in the risks of pulmonary embolism or death from any cause with either of the new drug groups compared with standard treatment.
- Both of the new drug groups were associated with significantly lower risk of bleeding compared with standard treatment: risk was 32% lower using direct thrombin inhibitors (OR 0.68, 95% CI 0.47 to 0.98), and 43% lower using factor Xa inhibitors (OR 0.57, 95% CI 0.43 to 0.76).
What does current guidance say on this issue?
NICE guidelines (2010, 2012) recommend the use of heparin, fondaparinux (another injected drug) and warfarin - or one of its related drugs - for most people with DVT or pulmonary embolism.
The newer drugs dabigatran (a direct thrombin inhibitor), apixaban and rivaroxaban (both factor Xa inhibitors) have been assessed individually by NICE (2013, 2014, 2015). All are currently recommended as options for all people with DVT or pulmonary embolism, having previously been restricted to certain groups, such as those having hip or knee replacement surgery.
What are the implications?
The newer oral drugs were found to be as effective as the standard treatment, which most commonly involves injections followed by warfarin, but were linked to a lower risk of bleeding, so may be safer.
Unlike warfarin, the new oral drugs do not require frequent monitoring or dose changes to try and maintain the delicate balance between clotting and bleeding risk. This would be more convenient for patients and also reduce the resources needed for monitoring clinics.
The lack of a reversal agent is of concern to some clinicians and patients. Fortunately, the need is relatively rare as the newer drugs have a short half-life (if renal function is good). Reversal agents to each of the new drugs are currently under trial and results are awaited.
The ease of use, in the short term, may also provide clinical and economic benefits in the avoidance of the warfarin loading phase of treatment. This is a step which needs injected anticoagulants and frequent blood tests, and is sometimes undertaken in hospital.
Overall the review supports the current recommendations of NICE (2013, 2014, 2015) that these drugs may be considered for the treatment of DVT or pulmonary embolism. The review did not look at overall cost or cost-effectiveness, but the NICE assessments include costing statements and tools that give further information on the individual drugs and could be useful to commissioners seeking cost data relevant to their populations. All these drugs are more expensive per day than warfarin.
Robertson L, Kesteven P, McCaslin JE. Oral direct thrombin inhibitors or oral factor Xa inhibitors for the treatment of deep vein thrombosis. Cochrane Database Syst Rev. 2015 Jun 30;6:CD010956.
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