Benefits and risks of anticoagulation resumption following traumatic brain injury.

IMPORTANCE: The increased risk of hemorrhage associated with anticoagulant therapy following traumatic brain injury creates a serious dilemma for medical management of older patients: Should anticoagulant therapy be resumed after traumatic brain injury, and if so, when?

OBJECTIVE: To estimate the risk of thrombotic and hemorrhagic events associated with warfarin therapy resumption following traumatic brain injury.

DESIGN, SETTING, AND PARTICIPANTS: Retrospective analysis of administrative claims data for Medicare beneficiaries aged at least 65 years hospitalized for traumatic brain injury during 2006 through 2009 who received warfarin in the month prior to injury (n = 10,782).

INTERVENTION: Warfarin use in each 30-day period following discharge after hospitalization for traumatic brain injury.

MAIN OUTCOMES AND MEASURES: The primary outcomes were hemorrhagic and thrombotic events following discharge after hospitalization for traumatic brain injury. Hemorrhagic events were defined on inpatient claims using International Classification of Diseases, Ninth Revision, Clinical Modification codes and included hemorrhagic stroke, upper gastrointestinal bleeding, adrenal hemorrhage, and other hemorrhage. Thrombotic events included ischemic stroke, pulmonary embolism, deep venous thrombosis, and myocardial infarction. A composite of hemorrhagic or ischemic stroke was a secondary outcome.

RESULTS: Medicare beneficiaries with traumatic brain injury were predominantly female (64%) and white (92%), with a mean (SD) age of 81.3 (7.3) years, and 82% had atrial fibrillation. Over the 12 months following hospital discharge, 55% received warfarin during 1 or more 30-day periods. We examined the lagged effect of warfarin use on outcomes in the following period. Warfarin use in the prior period was associated with decreased risk of thrombotic events (relative risk [RR], 0.77 [95% CI, 0.67-0.88]) and increased risk of hemorrhagic events (RR, 1.51 [95% CI, 1.29-1.78]). Warfarin use in the prior period was associated with decreased risk of hemorrhagic or ischemic stroke (RR, 0.83 [95% CI, 0.72-0.96]).

CONCLUSIONS AND RELEVANCE: Results from this study suggest that despite increased risk of hemorrhage, there is a net benefit for most patients receiving anticoagulation therapy, in terms of a reduction in risk of stroke, from warfarin therapy resumption following discharge after hospitalization for traumatic brain injury.