The Benefit of Dabigatran Over Warfarin Is Greater in Patients with Atrial Fibrillation and Diabetes Than in Nondiabetics

Introduction

The RE-LY study compared warfarin and dabigatran at doses of 110 mg and 150 mg in terms of reducing the incidence of stroke and systemic embolism over 2 years in 18,113 patients with atrial fibrillation. In 2009, it showed that dabigatran at a dose of 110 mg reduces the incidence of stroke and systemic embolism similarly to warfarin with a lower incidence of severe bleeding, and at a dose of 150 mg reduces the incidence of stroke and systemic embolism even more than warfarin, with a comparable incidence of severe bleeding.

Later, an analysis was conducted comparing the characteristics of patients and the relative efficacy of dabigatran and warfarin in groups of patients with diabetes and without diabetes.

Results

Diabetes mellitus was present in 4,221 study participants (23.3%). Patients with diabetes were on average younger (70.9 vs. 71.7 years). They were more likely to have hypertension (86.6 vs. 76.5%), coronary artery disease (37.4 vs. 24.9%), and peripheral atherosclerosis (5.6 vs. 3.2%; all p < 0.01).

Regardless of assigned treatment, the incidence of stroke and systemic embolism was higher in patients with diabetes (1.9 vs. 1.3 %/year; p < 0.001). Diabetics also had higher mortality (5.1 vs. 3.5 %/year; p < 0.001) and a higher incidence of severe bleeding (4.2 vs. 3.0 %/year; p <0.001).

Compared to warfarin, treatment with dabigatran led to a significantly greater absolute reduction in the incidence of stroke and systemic embolism in diabetics than in non-diabetics (dabigatran 110 mg: 0.59 vs. 0.05 %/year; dabigatran 150 mg: 0.89 vs. 0.51 %/year).

In the analysis of results in patients with diabetes by treatment groups, the incidence of stroke and systemic embolism was reduced by 39% (hazard ratio [HR] 0.61; 95% confidence interval [CI] 0.41–0.91) in the group treated with dabigatran 150 mg twice daily compared to warfarin and by 26% (HR 0.74; 95% CI 0.51–1.07) in the group treated with dabigatran 110 mg twice daily compared to warfarin. The incidence of severe bleeding was similar across all treatment groups. However, the incidence of intracranial bleeding was lower in patients treated with dabigatran.

Conclusion

The authors conclude that the benefit of the new oral anticoagulant (NOAC) dabigatran in the prophylaxis of embolic events in patients with atrial fibrillation compared to warfarin is greater in patients with diabetes than in nondiabetics.

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Source: Brambatti M., Darius H., Oldgren J. Comparison of dabigatran versus warfarin in diabetic patients with atrial fibrillation: results from the RE-LY trial. Int J Cardiol 2015; 196: 127−131, doi: 10.1016/j.ijcard.2015.05.141.