Results of a large study suggest warfarin may pose a higher risk of traumatic intracranial bleeding than previously reported, at least among older patients with atrial fibrillation (AF).
The study included more than 30,000 US veterans with AF who were 75 years or older when starting warfarin.
These patients had a higher rate of traumatic intracranial bleeding than reported in previous trials.
John A. Dodson, MD, of the New York University School of Medicine in New York, New York, and his colleagues conducted this research and reported the results in JAMA Cardiology.
The researchers studied 31,951 subjects with AF who were 75 years or older and were new referrals to Veterans Affairs anticoagulation clinics for warfarin therapy between January 1, 2002, and December 31, 2012.
The patients had a mean age of 81.1, and 98.1% were male. Comorbidities included hypertension (82.5%), coronary artery disease (42.6%), and diabetes mellitus (33.8%).
The researchers found the incidence rate of hospitalization for any intracranial bleeding among these patients was 14.58 per 1000 person-years.
And the incidence rate of hospitalization for traumatic intracranial bleeding was 4.80 per 1000 person-years.
The researchers said this was “considerably higher” than reported in two previous trials, one published in The Lancet in 1996 and one published in JAMA Internal Medicine in 1998.
Dr Dodson and his colleagues also looked at factors associated with traumatic intracranial bleeding in their patient population.
In unadjusted analyses, the following factors were significant predictors of traumatic intracranial bleeding: dementia, fall within the past year, anemia, depression, abnormal renal or liver function, anticonvulsant use, labile international normalized ratio, and antihypertensive use.
However, when the researchers adjusted their analyses for potential confounders, fewer factors remained significant predictors. These were dementia (hazard ratio [HR]=1.76), anemia (HR=1.23), depression (HR=1.30), anticonvulsant use (HR=1.35), and labile international normalized ratio (HR=1.33).
The researchers noted that risk factors for traumatic intracranial bleeding were different from risk factors for ischemic stroke.
They also said the high overall rate of intracranial bleeding in this study suggests a need to more systematically evaluate the benefits and harms of warfarin in older adults.
