Pradaxa (dabigatran) can now be considered for the prevention of stroke and systemic embolism in at-risk patients with atrial fibrillation (AF), as an alternative to warfarin. Unlike warfarin, no loading dose is required with dabigatran, nor regular blood tests to monitor INR. However, the monitoring of dabigatran-related anticoagulation may be helpful to prevent dabigatran overexposure in the presence of additional risk factors eg, ≥75 years, renal impairment or low body weight.
In the non-inferiority RE-LY study, 18113 patients with AF and risk factors for stroke were randomised and allocated to receive either dabigatran, blinded and using fixed doses of 110mg or 150mg twice daily, or open-label warfarin, adjusted according to INR. Rate of stroke or systemic embolism was used as the primary efficacy measure. Additionally, the rate of major bleed was identified as a measure of safety and defined as a ≥20g/litre reduction in haemoglobin level, transfusion of ≥2 units of blood, or symptomatic bleeding in a critical area or organ. The median duration of follow up was 2.0 years.
Results found dabigatran to be non-inferior to warfarin in reducing the rate of stroke or systemic embolism at the lower dose and displayed superior efficacy at the higher dose (rate per year: warfarin 1.71%; low dose dabigatran 1.54%; high dose dabigatran 1.11% [95% CI; p<0.001 for non-inferiority and superiority, respectively]).
The rates of major bleed were comparable between the warfarin and high dose dabigatran groups (relative risk 0.93 [95% CI; p<0.32]) but significantly lower when comparing the warfarin and low dose dabigatran group (relative risk 0.80 [95% CI; p<0.003]).
Only Pradaxa 110mg and 150mg capsules are licensed for this new indication.