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Dabigatran has significantly lower bleeding rates compared with warfarin in patients with atrial fibrillation

Large trials have established that non-vitamin K antagonist oral anticoagulants are as effective as warfarin in preventing ischaemic stroke.

Atrial fibrillation is associated with an increased risk of ischaemic stroke and mortality.

In the past five years, large randomised trials have established that non-vitamin K antagonist oral anticoagulants (novel oral anticoagulants (NOACs)) are as effective as warfarin in preventing ischaemic stroke, but also substantially reduce the risk of associated intracranial haemorrhage.

Dabigatran is a non-vitamin K antagonist oral anticoagulant. Picture: Science Photo Library

Guidelines now recommend NOACs as first choice of drug. While meticulous dose adjustments are not required for NOACs as they are for warfarin, a clinical evaluation of appropriate dose is still necessary. Age and chronic kidney disease in patients with atrial fibrillation increase the risk of bleeding during anti-thrombotic treatment.

Older patients with atrial fibrillation were included in early trials but comprised only a small proportion of the patient populations. This study looked at 55,644 patients (average age 73.9) with atrial fibrillation who were prescribed either apixaban 2.5mg, dabigatran 110mg, rivaroxaban 15mg or warfarin.

While there were slightly higher rates of ischaemic stroke or systemic embolism with apixaban compared with warfarin, this was not statistically significant. Rates of bleeding, the principal safety outcome, were no different for apixaban or rivaroxaban when compared with warfarin, but dabigatran was found to have significantly lower rates of bleeding. Doses of dabigatran should, however, be reduced for those aged over 80 or with reduced renal function.

Nielsen P, Skjøth F, Søgaard M et al (2017) Effectiveness and safety of reduced dose non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study. BMJ. 356:j510. doi:10.1136/bmj.j510

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