Clinical question: Can you use aspirin as a safe alternative to low-molecular-weight heparin (LMWH) for thromboprophylaxis in patients with an extremity fracture?
Background: Many guidelines recommend thromboprophylaxis therapy to reduce the risk of venous thromboembolism and its complications after traumatic orthopedic injuries. Even though there is a preference amongst patients for aspirin, given the lower cost and oral administration, there are limited studies comparing aspirin and LMWH among patients who have been treated operatively.
Study design: Pragmatic, multicenter, randomized, noninferiority trial
Setting: 21 trauma centers in the U.S. and Canada
Synopsis: This study included 12,211 patients 18 years of age or older who had an extremity fracture that was treated operatively or a fracture of the pelvis or acetabulum that was treated operatively or nonoperatively. Patients were randomly assigned to receive LMWH at a dose of 30 mg twice daily or aspirin at a dose of 81 mg twice daily while they were in the hospital. After hospital discharge, the patients continued to receive thromboprophylaxis according to the clinical protocols of each hospital. During the 90-day follow-up period, aspirin was non-inferior to LMWH (P <0.001) but not superior (P=0.63) in preventing death from any cause. Deep-vein thrombosis occurred in 2.51% of patients in the aspirin group and 1.71% in the LMWH group (difference, 0.80 percentage points; 95% CI, 0.28 to 1.31). The incidence of pulmonary embolism (1.49% in each group), bleeding complications, and other serious adverse events were similar in the two groups. One of the limitations of this study was the differences in the duration of thromboprophylaxis therapy after hospital discharge, which may have influenced outcomes.
Bottom line: Thromboprophylaxis with aspirin was non-inferior to LMWH for the prevention of fatal events in patients with orthopedic trauma and was associated with low frequencies of deep-vein thrombosis, pulmonary embolism, and death from any cause at 90 days.
Citation: Major Extremity Trauma Research Consortium (METRC), et al. Aspirin or low-molecular-weight heparin for thromboprophylaxis after a fracture. N Engl J Med. 2023;388(3):203-13.
Dr. Rinaldi
Dr. Rinaldi is a hospitalist at Atrium Health Wake Forest Baptist, and an assistant professor in internal medicine at Wake Forest University School of Medicine, both in Winston-Salem, N.C.
We don’t expect LMWH to necessarily reduce death, it is for DVT reduction which it appears to be superior for. I think the focus on death a a primary end point was misguided and drew attention away from the higher rate of DVT with ASA.