A recent analysis of previous data found that while warfarin and dabigatran are comparable at preventing stroke in patients with atrial fibrillation who have previously had a stroke or transient ischemic attack, the risk of developing intracranial bleeding is lower with dabigatran.
The study, led by Hans-Christoph Diener, MD, of University Hospital Essen in Germany, aimed to analyze a subgroup of patients from the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial.
The RE-LY trial found that 110 mg dabigatran twice daily was as effective as warfarin in reducing the occurrence of stroke, and that 150 mg dabigatran twice daily was better than warfarin in patients who had atrial fibrillation.
Twenty percent of the participants had previously had a stroke or transient ischemic attack, which increases the risk of having another stroke. Dr Diener and colleagues decided to look at this subgroup because they are more susceptible to adverse events from anticoagulation, especially cerebral hemorrhage.
It is important to note that one of warfarin’s negative side effects is bleeding.
The investigators found that warfarin and both dosages of dabigatran were equally effective in preventing stroke or systemic embolism in patients with a previous transient ischemic attack or stroke.
Compared with warfarin, the relative risk (RR) of stroke or systemic embolism with the 150 mg dose of dabigatran was 0.75 and for the 110 mg dose was 0.84.
The rate of major bleeding was significantly lower in patients on 110 mg dabigatran (RR 0.66) and similar in those on 150 mg dabigatran (RR 1.01) compared with those on warfarin.
The 110 mg dose of dabigatran was also associated with a significant reduction in the rate of vascular death (RR 0.63) and all-cause mortality (0.70).
According to the authors, “The exact mechanism for the lower rate of intracranial bleeding with dabigatran compared with warfarin, beyond a more stable anticoagulation, is not yet known. One possible explanation is that dabigatran does not cross the blood-brain barrier.”
When it comes to choosing a dosage, the authors concluded, “The dose of 150 mg dabigatran twice daily could be preferred to 110 mg twice daily because it significantly reduces the risk of ischemic stroke without increasing the risk of hemorrhagic stroke."
The study was funded by Boehringer Ingelheim and published online first by The Lancet Neurology.
