Many patients who are prescribed to direct oral anticoagulants (DOAC) for atrial fibrillation (AF) and/or venous thromboembolism (VT) are also treated with concurrent acetylsalicylic acid (ASA or aspirin). However, the outcomes following the use of aspirin after DOAC treatment is unclear. This study aims to identify how many patients assigned to DOAC are given aspirin and how it affects clinical outcomes.

This registry-based cohort study included a total of 3,280 adult patients who were undergoing treatment with a DOAC for AF or VTE. The primary exposure was the use of ASA concomitant with DOAC therapy. The main outcomes of the study were rates of bleeding, thrombosis, emergency department (ED) visits, hospitalizations, and death.

Of 3,280 patients included in the study, 1,107 patients (33.8%) without a clear indication for ASA were being treated with DOACs and ASA. During a mean follow-up of 20.9 months, patients taking DOAC and ASA experienced more bleeding events compared with those undergoing DOAC monotherapy. Patients undergoing combination therapy had significantly higher rates of nonmajor bleeding compared with monotherapy; however, the instances of major bleeding were similar in both groups.

The research concluded that patients who were treated with DOACs and ASA were at a higher risk of nonmajor bleeding.