Warfarin given to elderly patients within a year of traumatic brain injury associated with net benefit

Resuming warfarin in the year after a traumatic brain injury was associated with a net benefit, due to a reduction in ischemic stroke risk, for elderly patients in a recent study.

The retrospective analysis used Medicare claims data to follow more than 10,000 patients 65 and over who were hospitalized for traumatic brain injury in 2006 to 2009 and had taken warfarin in the month prior to their injury. The patients were predominately female and white, and 82% had atrial fibrillation. Results were published in JAMA Internal Medicine on June 10.

The study lacked data on warfarin use in a number of patients because they were discharged to a skilled nursing facility, but the researchers examined whether a patient had a prescription for warfarin in various time periods after discharge. A month after discharge 26% used warfarin, 46% didn't, and 28% were missing information. By 3 months after discharge, the proportion who had taken warfarin was up to 44%, with 12% missing. Overall, the study found that only 55% of the patients received warfarin at some point during the year following hospitalization. Fewer than 10% of patients used another anticoagulant.

The researchers used a lagged effect to calculate the delayed impact of warfarin usage on their primary outcomes—hemorrhagic and thrombotic events, including hemorrhagic or ischemic stroke, gastrointestinal bleeding, pulmonary embolism, deep venous thrombosis, and myocardial infarction. They calculated that warfarin use was associated with a decreased risk of thrombotic events (relative risk [RR], 0.77; 95% CI, 0.67 to 0.88) and an increased risk of hemorrhagic events (RR, 1.51; 95% CI, 1.29 to 1.78). Overall stroke risk was lower in the time period after patients had taken warfarin (RR, 0.83; 95% CI, 0.72 to 0.96).

The results show that most traumatic brain injury patients would receive a net benefit from resuming warfarin therapy, unless there is a strong contraindication, the study authors concluded. They noted that older patients and those with Alzheimer's disease were less likely to receive warfarin in the study, consistent with existing evidence about physicians' fears of bleeding and fall risk. This study provides more objective information to help them and their patients make informed treatment decisions, the authors wrote.