Incidence, risk factors for intracranial bleeding in older adults newly prescribed warfarin

John A. Dodson, M.D., M.P.H., of the New York University School of Medicine, and colleagues conducted a study that included 31,951 U.S. veterans with atrial fibrillation, 75 years or older, who were new referrals to Veterans Affairs (VA) anticoagulation clinics (for warfarin therapy) between 2002 and 2012. The study was published online by JAMA Cardiology.

Advanced age is a powerful risk factor for thromboembolic stroke in patients with atrial fibrillation (AF), and oral anticoagulation reduces this risk by almost two-thirds in patients at risk. Traumatic intracranial bleeding, which is most commonly attributable to falls, is a common concern among health care professionals, who are hesitant to prescribe oral anticoagulants to older adults with AF.

The researchers found that the rate of traumatic intracranial bleeding among older adults with AF initiating warfarin therapy was higher than previously reported in clinical trials. Several factors placed patients at increased risk of traumatic intracranial bleeding, including dementia, anemia, depression, anticonvulsant use, and labile (unstable) international normalized ratio (INR).

"While we were unable to generate a clinical prediction tool to evaluate risk given poor model discrimination, we still believe that the individual factors we identified may potentially be used in patient-centered discussions about the benefits and harms of warfarin therapy in older adults. Our findings should be validated in other data sets, particularly given the under-representation of women in our sample," the authors write.