Increase In Subdural Hematomas Associated With Increase Use of Antithrombotic Drugs Interview with:

David Gaist, MD, PhD</strong> Department of Neurology Odense University Hospital University of Southern Denmark Odense, Denmark

Dr. David Gaist What is the background for this study? What are the main findings?

Response: The incidence of subdural hematoma (SDH; a bleed located within the skull, but outside the brain) has been reported to be on the increase. Previous studies have shown an association between use of antithrombotic drugs and SDH. However, studies with updated estimates of this risk and with focus on current more complex and aggressive regimens of antithrombotic treatment are scarce.

We therefore performed this study, where we identified 10,010 patients aged 20-89 years that were admitted with SDH in Denmark in 2000 through 2015. Preadmission use of antithrombotic drugs (low-dose aspirin, clopidogrel, vitamin K antagonist, e.g. warfarin, and direct oral anticoagulants) of these cases was compared to that of 400,380 individuals from the general population with no history of SDH (controls).

We found that use of antithrombotic drugs was associated with an increased risk of subdural hematoma . The magnitude of this risk varied by type of antithrombotic, and was, e.g., low for use of low-dose aspirin, and highest for warfarin. Further, with a single exception (low-dose aspirin and dipyridamole), concurrent use of more than one antithrombotic drug was associated with higher risk of SDH, particularly if warfarin was taken along with an antiplatelet drug, e.g., low-dose aspirin or clopidogrel. Increasing use of antithrombotic drugs was observed in the study period. The incidence of subdural hematomas in the Danish population also increased markedly in the years 2000-2015, particularly among those aged 75+ years. Our study indicates that this increased incidence, can, at least partly, be explained by increased use of antithrombotic drugs. What should readers take away from your report?

Response: Use of antithrombotic drugs is associated with increased risk of SDH, but the size of this risk depends on the type of antithrombotic, and the regimen (i.e., mono- vs. polytherapy). Increased use of these drugs is reflected in an increased risk of the occurrence of this type of intracranial bleed.

The present data add one more piece of evidence to the complex risk-benefit equation of antithrombotic drug use. It is important to emphasize that these drugs result in net benefits overall in patients with clear therapeutic indications. What recommendations do you have for future research as a result of this study?

Response: Future research should focus on delineating risk of subdural hematomas in particular subgroups of patients taking antithrombotics. This might lead to identification of modifiable risk factors for SDH and, ultimately, pave the way for reducing its occurrence. Is there anything else you would like to add? Any disclosures?

Response: For disclosures, please see full article available at JAMA.
This study was conducted in collaboration with the Department of Neurosurgery, Odense University Hospital, the Department of Clinical Pharmacology, University of Southern Denmark, and with the Spanish Centre for Pharmacoepidemiologic Research, Madrid, Spain. The study received no funding.


Association of Antithrombotic Drug Use With Subdural Hematoma Risk
David Gaist, MD, PhD; Luis Alberto García Rodríguez, MD; Maja Hellfritzsch, MD; Frantz Rom Poulsen, MD, PhD; Bo Halle, MD, PhD; Jesper Hallas, MD, DrMSc; Anton Pottegård, MScPharm, PhD
JAMA February 28, 2017 Volume 317, Number 8

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