Original Paper

Increased Risk of Intracranial Hemorrhage when Aspirin Is Combined with Warfarin: A Meta-Analysis and Hypothesis
Robert G. Hart^a, Oscar Benavente^a, Lesly A. Pearce<sup>b

a</sup>Department of Medicine/Division of Neurology, University of Texas Health Science Center in San Antonio, Tex., USA;
^bStatistics and Epidemiology Research Corp., Seattle, Wash., USA

Address of Corresponding Author

Cerebrovasc Dis 1999;9:215-217 (DOI: 10.1159/000015958)

  Key Words

• Aspirin
• Antiplatelet agents
• Warfarin
• Anticoagulation
• Intracerebral hemorrhage
• Intracranial hemorrhage
• Metanalysis

  Abstract

Background: Oral anticoagulation with vitamin K antagonists increases the risk of intracranial hemorrhage; whether addition of aspirin to oral anticoagulation augments this risk is unclear. Methods: Meta-analysis of randomized clinical trials in which aspirin was added to oral anticoagulants. Results: Six randomized clinical trials were identified, including a total of 3,874 participants. Use of aspirin with oral anticoagulants was associated with more than double the frequency of intracranial hemorrhage (relative risk = 2.4, 95% CI = 1.2-4.8, p = 0.02). Conclusion: We hypothesize that aspirin when added to oral vitamin K antagonists may increase the risk of intracranial hemorrhage, but this observation requires confirmation. The magnitude of this effect is uncertain, and the clinical importance is likely different for different patient populations.

  Author Contacts

Robert G. Hart, MD
Department of Medicine/Division Neurology
University of Texas Health Science Center in San Antonio
7703 Floyd Curl Drive, San Antonio, TX 78284-7883 (USA)
Tel. +1 (210) 617 5161, Fax +1 (210) 567 4659, E-Mail hartr@uthscsa.edu

  Article Information

Received: Received: August 19, 1998
Accepted: October 26, 1998
Number of Print Pages : 3
Number of Figures : 0, Number of Tables : 1, Number of References : 18