The direct oral anticoagulant (DOAC) drugs apixaban, dabigatran, and rivaroxaban are associated with a lower risk of osteoporotic fracture than is warfarin in patients with atrial fibrillation (AFib), according to a new retrospective analysis.
There was no difference in risk between individual DOAC medications.
The study drew from an EHR database of the Hong Kong Hospital Authority. It was led by Wallis C.Y. Lau, PhD, of the University of Hong Kong and appeared online May 19 in Annals of Internal Medicine.
Warfarin is suspected to contribute to osteoporotic fracturing in AFib patients, but previous studies returned mixed results. The more recently introduced DOACs were not tested for fracture risks, and it hasn’t been determined if individual DOACs have different risks. The question is even more important in AFib, in which patients are older and often have comorbidities that could predispose them to fractures.
The study included 23,515 patients with AFib who used anticoagulants. 3,241 used apixaban, 6,867 dabigatran, 3,866 rivaroxaban, and 9,541 used warfarin. The median follow-up was 423 days.
According to Cox proportional hazards model analyses, DOAC use was associated with fewer fractures than was warfarin (hazard ratio for apixaban vs. warfarin, 0.62; 95% confidence interval, 0.41-0.94; HR for dabigatran, 0.65; 95% CI, 0.49-0.86; HR for rivaroxaban, 0.52; 95% CI, 0.37-0.73). Subanalyses in men and women showed similar results (P for interaction >.05).
Head-to-head comparisons between individual DOACs yielded no statistically significant differences in osteoporotic fracture risk.
Although the findings couldn’t absolutely rule out a difference in osteoporotic fracture risk between different DOACs, the authors argue that any clinical significance would likely be small.
“Given the supportive evidence from experimental settings, findings from our study using clinical data, and the indirect evidence provided by the previous meta-analysis of randomized, controlled trials, there exists a compelling case for evaluating whether the risk for osteoporotic fractures should be considered at the point of prescribing an oral anticoagulant to minimize fracture risk,” the authors wrote.
The study is limited by the potential for residual confounding, the investigators noted.
The study was funded by the University of Hong Kong and University College London Strategic Partnership Fund.
SOURCE: Lau WCY et al. Ann Intern Med. 2020 May 19. doi: 10.7326/M19-3671.