Is Warfarin-Related Bleeding Risk Affected by Age?

In adults aged 80 and older, warfarin was associated with only slight increases in bleeding risk, although it was also associated with significant increases in the risk of thrombosis, according to the results of a recent study.

While previous studies have shown that despite their increased bleeding risk, elderly patients still benefit from anticoagulation therapy, little data are available for patients older than 90 years.
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For this reason, the researchers conducted a matched cohort study of 1109 patients aged 90 years and older treated with a vitamin K antagonist (VKA) matched with 1100 patients aged 80 to 89 and 1104 patients aged 70 to 79, based on duration of VKA treatment.

The primary outcome of the study was a composite of clinically relevant nonmajor and major bleeding, with secondary outcomes of thromboses and quality of VKA control.

Overall, 713 of the 3313 participants had 1050 bleeding events. In patients aged 80 to 89, the risk of bleeding was not significantly increased, and the risk was only mildly increased in patients 90 years and older, compared with patients aged 70 to 79. Eighty-five patients developed a thrombotic event, and the risk of thrombosis was higher for patients aged 80 to 89 and over age 90 than for those aged 70 to 79.

“These clinical practice data of patients considered eligible for anticoagulation show that the bleeding risk with a VKA only mildly increases after the age of 80 years, while there is a sharp increase in the risk of thrombosis in the same age group.”

—Michael Potts

Reference:

Kooistra HAM, Calf AH, Piersma-Wichers M, et al. Risk of bleeding and thrombosis in patients 70 years or older using vitamin K antagonists [published online July 5, 2016]. JAMA Intern Med. doi:10.1001/jamainternmed.2016.3057.