Aspirin plus DOAC is not better than a DOAC alone

Patients with atrial fibrillation or a history of venous thromboembolism (VTE) who take daily aspirin in addition to a prescribed direct oral anticoagulant (DOAC) to treat or prevent blood clots had significantly higher rates of bleeding complications compared with those taking a DOAC alone. Researchers found no differences in stroke, heart attack, or blood clots between the groups after 1 year [1].

Of the 2,045 patients in the study, 647 (32%) reported taking aspirin in addition to a prescribed DOAC, even though their medical history did not clearly indicate that need. Prof. Jordan Schaefer (University of Michigan, USA) compared 2 matched groups of 639 patients that had similar demographics, co-morbidities, and concurrent medications. Of the patients taking aspirin, the vast majority (90.3%) were taking low-dose aspirin (≤100 mg per day). Patients taking a DOAC alone had 261 319 bleeding events, compared with 319 261 bleeding events by those taking a DOAC plus aspirin; a 22% increase in bleeds over an average follow-up of 15 months. This difference was largely driven by clinically relevant non-major bleeding events, which were nearly 40% higher with dual therapy. Bleeding sites were most commonly bruising, intestinal bleeding, or bleeding through the urinary tract. Observed rates of thrombosis (stroke, VTE, and heart attacks) were similar between patients taking both medicines and those only on a DOAC (19 and 18 events, respectively).

The only 2 fatal bleeding events were seen among patients on DOACs only. Patients on dual therapy had more emergency room visits and hospitalisations mostly due to bleeding, but these differences did not reach statistical significance.

Prof. Schaefer said, “Based on our findings, adding aspirin may do more harm than good for some patients, increasing bleeding rates without improvements in the incidence of thrombosis.” He also indicated that he hopes these data will raise awareness within the medical community and lead to reducing the number of patients inappropriately taking aspirin.

1. Schaefer J, et al. Abstract 787, ASH 2019, 7-10 December, Orlando, USA.

Posted on 5 March 20206 September 2023