12,211 patients from 21 trauma centers in the United States and Canada were included in this non-inferiority randomized trial comparing aspirin (n=6,101) and low molecular-weight heparin (n=6110). The primary outcome of interest was death by any cause at 90 days. Secondary outcomes of interest included the risk of thromboembolic events (pulmonary embolism; deep-vein thrombosis), cause-specific death, bleeding & wound complications, and the rate of infection. Aspirin was found to be non-inferior to low molecular-weight heparin with respect to the primary outcome of death by any cause. No differences in all secondary outcomes were observed between the two groups, with the exception of the rate of deep vein thrombosis (any; distal), which was higher in the aspirin group.