Clinical research studyDeath and Disability from Warfarin-Associated Intracranial and Extracranial Hemorrhages
Section snippets
Cohort Assembly and Ascertainment of Patient Characteristics
The AnTicoagulation and Risk Factors In Atrial Fibrillation (ATRIA) Study is a cohort of 13,559 adults with diagnosed nonvalvular atrial fibrillation who received care within Kaiser Permanente of Northern California, a large integrated health care delivery system. Details of the cohort assembly have been described.9 Cohort members were identified by searching automated inpatient, outpatient, and electrocardiographic databases for physician-assigned International Classification of Diseases,
Results
During the study period, we identified 72 patients hospitalized with a validated warfarin-associated intracranial hemorrhage during 15,370 person-years of follow-up on warfarin therapy (unadjusted annualized rate 0.47%, 95% confidence interval [CI], 0.37%-0.59%). Of these, 51 (71%) were intracerebral, 15 (21%) were subdural, and 6 were other or unknown types of intracranial hemorrhages. We also identified 98 patients with a validated warfarin-associated major extracranial hemorrhage during
Discussion
Intracranial hemorrhages accounted for approximately 90% of the deaths caused by warfarin-associated hemorrhage, and most of the functional disability among survivors in this cohort of patients taking warfarin for atrial fibrillation. Although the overall rate of hemorrhagic events in the cohort was relatively low, of those patients who sustained a complication from warfarin, intracranial hemorrhage was the primary determinant of death and disability.
The approximately 50% mortality rate from
Conclusion
Intracranial hemorrhages are the primary determinant of poor outcomes from warfarin-associated hemorrhage, resulting in substantially higher rates of death and disability than major extracranial hemorrhages. As a consequence, rather than basing the anticoagulation decision on a patient’s risk for hemorrhage of all types, clinicians should depend primarily on a comparison of the patient’s ischemic stroke risk without warfarin therapy with the risk of intracranial hemorrhage with warfarin
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This work was supported by Public Health Services research grant AG15478 from the National Institute on Aging, the Eliot B. and Edith C. Shoolman Fund of Massachusetts General Hospital, and a Hartford Geriatrics Health Outcomes Research Scholars Award from the AGS Foundation for Health in Aging.