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Choosing Antithrombotic Therapy for Elderly Patients With Atrial Fibrillation Who Are at Risk for Falls
Study Questions:
Should the risk of falling influence the choice of antithrombotic therapy in elderly patients with atrial fibrillation?
Methods:
The authors created a decision analytic Markov model of three different strategies (no antithrombotic therapy, long-term aspirin use, or long-term warfarin use) for managing subjects over age 65 with atrial fibrillation, who are at risk for falling, and have no other contraindications to antithrombotic therapy. Stroke outcome was considered as five possible states: well; minor, moderate, or major disability; or dead. Input data, to evaluate risk of stroke after each treatment strategy and falls, were obtained by systematic review of MEDLINE. Overall outcomes were expressed as quality-adjusted life-years (QALYs).
Results:
The authors reported that of 190 relevant scientific studies reviewed, 49 met the inclusion criteria. Models created suggested that for average risk of stroke and falls, no antithrombotic therapy was associated with 10.15 QALYS, aspirin therapy with 11.17 QALYs, and warfarin therapy with 12.90 QALYs. Sensitivity analysis suggested that, regardless of age or baseline stroke risk, risk of falling has no effect on determining optimal antithrombotic therapy.
Conclusions:
The authors concluded that, for elderly patients with atrial fibrillation, the choice of optimal therapy to prevent stroke depends on many clinical factors, especially their baseline risk of stroke. However, patients’ propensity to fall is not an important factor in this decision.
Perspective:
It has been known for some time that the risk of stroke in elderly patients with atrial fibrillation, on average, hovers near 5-6%, and higher with added risk factors. It is also well known that subdural hematoma (SDH) and intracranial hematoma (ICH) are quite rare, even in elderly patients receiving warfarin (in the current literature review and analysis, SDH and ICH risk annually, for elderly patients on warfarin, are 0.14% and 0.7%, respectively). This makes the risk of stroke off warfarin roughly 9 times the risk of ICH or SDH on warfarin. Nonetheless, the fear of SDH has frequently been cited as a reason to withhold warfarin from elderly patients, especially those at risk for, or with a history of, falls (possibly influenced by personal experience, as SDH is often associated with falls.) The current analysis puts a statistically fine point on the fact that a risk of falls does not have any measurable effect on the decision to anticoagulate patients with atrial fibrillation. (The authors went on to calculate that, given the true risk of SDH after a fall, persons taking warfarin must fall about 295 times in 1 year for warfarin to not be the optimal therapy.) When one further considers that the risk of stroke in AF without warfarin—and therefore the benefit of warfarin—goes up rather dramatically with increasing age, the benefit of warfarin is likely to only increase with greater age.
Keywords: Stroke, Intracranial Hemorrhages, Cardiology, Warfarin, Risk Factors, Hematoma
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