Myles et al. have used a 2-by-2 factorial trial design to randomly assign patients who were scheduled to undergo coronary artery surgery and were at risk for perioperative complications to receive aspirin or placebo and tranexamic acid or placebo. They report the results of the aspirin trial.
Patients were randomly assigned to receive 100 mg of aspirin or matched placebo preoperatively, as a unique dose. Physicians had no limitation to the use of postoperative aspirin or other antiplatelet therapy, and such therapy was administered in accordance with local practices. This means that a single dose of 100 mg aspirin (1047 patients) was compared with placebo (1053 patients).
The results are clear-cut and they cannot surprise the reader: compared with placebo, preoperative administration of aspirin neither decreased the risk of death or thrombotic complications nor increased the risk of bleeding, transfusion or reoperation. However, major criticisms can be made. The authors have to be commended for their willingness to demonstrate that aspirin does not increase perioperative bleeding and that withdrawing aspirin could increase the thrombotic risk. Nevertheless, the concept of this study is amazing: how could a single dose of 100 mg aspirin, with no loading dose, have a positive or negative effect?
This study started to enroll patients in 2004 and the design was published in 2008. Since then, many procedures have changed. Intraoperative bleeding has also decreased. In addition, no information is provided regarding the re-start of any antiplatelet therapy after surgery. Which agent? When? Which dose? As a result, despite the large number of patients included in the study, nothing can be concluded with such a strange design!
– Charles-Marc Samama