According to new research findings, there appears to be a clinical advantage when direct oral anticoagulants (DOACs) are prescribed for atrial fibrillation (AF), compared with warfarin, in patients at risk for osteoporosis. Until now, it has been uncertain whether the specific anticoagulant class, or specific agent within class, is associated with an increased risk of osteoporotic fracture.
In research published in Annals of Internal Medicine in May 2020, scientists explored the potential differences between blood-thinning options. As the healthcare community continues to learn more about these agents, researchers explore and define parameters wherein improved profiles may benefit special populations, and in this case possibly minimize this associated, deleterious, and serious adverse drug outcome.
Funded by The University of Hong Kong and University College London Strategic Partnership Fund, first author, Wallis C.Y. Lau, PhD, from the University College London School of Pharmacy, and his team compared the risk for fracture due to osteoporosis in 23,515 patients who were newly diagnosed with AF and also received a new prescription for either warfarin or a DOAC. There were 9,541 warfarin users compared with those prescribed apixiban, dabigatran, and rivaroxaban, with each comparative cohort including 3,241, 6,867, and 3,866 subjects, respectively. The data for this population-based cohort study was extracted from the Hong Kong Hospital Authority electronic health record database, which spanned a 7-year timeframe (2010-2017), with the median follow-up of 423 days ending in December 2018.
Overall mean age was 74.4 years (standard deviation, 10.8), ranging from age 73.1 years for the youngest subject identified in the warfarin group to the oldest subject, age 77.9 years, taking apixaban. The team reported that over this period, 401 fractures (osteoporotic hip or vertebral fractures) were documented as a weighted rate per 100 patient years. Using propensity score–weighted cumulative incidence differences (CIDs), Dr. Lau and colleagues discovered that the majority of fractures were associated with warfarin use (196 [1.11]), followed in descending order by dabigatran (95 [0.76]), rivaroxaban (57 [0.67]), and apixaban (53 [0.82]).
The team concluded that DOAC use was associated with a lower risk for fracture than warfarin use (apixaban CID, 0.88% [95% CI, 1.66%- 0.21%]; dabigatran CID, 0.81% [CI, 1.34%-0.23%]; and rivaroxaban CID, 1.13% [CI, 1.67%-0.53%]). However, they wrote that “no differences were seen in all head-to-head comparisons between DOACs at 24 months (apixaban vs. dabigatran CID, 0.06% [CI, 0.69% to 0.49%]; rivaroxaban vs. dabigatran CID, 0.32% [CI, 0.84% to 0.18%]; and rivaroxaban vs. apixaban CID, 0.25% [CI, 0.86% to 0.40%]).”
According to the authors, “Among patients with AF, DOAC use may result in a lower risk for osteoporotic fracture compared with warfarin use. Fracture risk does not seem to be altered by the choice of DOAC. These ﬁndings may help inform the beneﬁt–risk assessment when choosing between anticoagulants.”
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