Atrial fibrillation: choice of anticoagulant may influence fracture risk

  • Binding C & al.
  • J Am Coll Cardiol
  • 29 Oct 2019

  • International Clinical Digest
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Takeaway

  • Among older adults with non-valvular atrial fibrillation (Afib), those receiving direct oral anticoagulants (DOACs) had lower risks for several fracture outcomes relative to those receiving vitamin K antagonists (VKAs).

Why this matters

  • Fractures have considerable morbidity and mortality in the geriatric population.

Key results

  • Standardised absolute 2-year risk for any fracture:
    • 3.09% among DOAC-treated patients.
    • 3.77% among vitamin K antagonist-treated patients.
  • Vs vitamin K antagonists, DOACs carried lower 2-year adjusted risks for:
    • Any fracture (HR, 0.85; P=.019).
    • Major osteoporotic fractures (HR, 0.85; P=.043).
    • Initiation of osteoporotic medication (HR, 0.82; P=.008).
    • Composite of any fracture and/or initiation of osteoporosis medication (HR, 0.84; P<.001>
  • Treatment with DOACs vs vitamin K antagonists:
    • 6.8 fewer osteoporotic fractures per 1000 persons treated (number needed to treat, 147).
    • 7.1 fewer initiations of osteoporosis medication per 1000 persons treated (number needed to treat, 141).

Expert comment

  • “[R]esidual confounding may have exaggerated the association,” Brian F. Gage, MD, MS, writes in an editorial. “Thus, at least for patients who have AF and no prior osteoporotic fracture (the population studied), the decision to prescribe a VKA or a DOAC should depend on the risks of ischaemic stroke, haemorrhage, need for monitoring, and affordability rather than on the risk of osteoporotic fracture.”

Study design

  • Danish nationwide retrospective cohort study of 37,350 older adults with nonvalvular Afib receiving at least 180 days of oral anticoagulant therapy who had not previously used osteoporosis medications.
  • Main outcomes: hip fracture, major osteoporotic fracture, any fracture, initiation of osteoporosis medication, composite endpoint.
  • Funding: Copenhagen University Hospital Herlev and Gentofte.

Limitations

  • Potential residual, unmeasured confounding.
  • Unknown generalisability.