medwireNews: A Danish nationwide cohort study published in The BMJ examines the effectiveness and safety profiles of novel oral anticoagulants (NOACs) among patients with atrial fibrillation (AF).
Using individual linked data from 55,644 patients included in three registries, the researchers assessed the incidence of thromboembolic and bleeding events in participants treated with NOACs (reduced dose non-vitamin K antagonist oral anticoagulants) versus warfarin.
Of 4400 patients treated with apixaban, 205 experienced ischemic stroke or systemic embolism during the first year of follow-up, translating into the highest propensity-weighted event rate of the four treatments at 4.78%.
By comparison, 325 of 8875 patients treated with dabigatran, 92 of 3476 treated with rivaroxaban, and 1157 of 38,893 treated with warfarin experienced thromboembolic events at 1 year, with corresponding weighted event rates of 3.31%, 3.53%, and 3.74%.
And at 2.5 years of follow-up, weighted thromboembolic event rates were 3.98%, 2.73%, 2.72%, and 2.68% for the apixaban, dabigatran, rivaroxaban, and warfarin groups, respectively, report the authors.
Although Torben Bjerregaard Larsen (Aalborg University) and colleagues say these findings suggest “a trend towards” higher rates of thromboembolic events with apixaban and lower rates with dabigatran and rivaroxaban compared with warfarin, they emphasize that the rates were not significantly different.
The 1-year weighted bleeding rates were “similar” among patients in the apixaban, rivaroxaban, and warfarin groups (5.12 and 5.58 vs 5.11%, respectively), whereas dabigatran was associated with a significantly lower rate of bleeding compared with warfarin, at 4.09% (hazard ratio=0.80). Similar associations between NOAC treatment and bleeding risk were found at 2.5 years of follow-up.
The researchers caution that their findings should be interpreted in light of the limitations associated with observational investigations, but note that the large study provided “the opportunity to ascertain how NOACs perform in clinical practice under usual clinical conditions.”
And they recommend that “future studies on reduced dose NOAC versus warfarin are still warranted and should preferably analyse effectiveness and safety outcomes in respect to label adherence.”
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