Effect of Aspirin Versus Low-Molecular-Weight Heparin Thromboprophylaxis on Medication Satisfaction and Out-of-Pocket Costs: A Secondary Analysis of a Randomized Clinical Trial

Background: Current guidelines recommend low-molecular-weight heparin for thromboprophylaxis after orthopaedic trauma. However, recent evidence suggests that aspirin is similar in efficacy and safety. To understand patients' experiences with these medications, we compared patients' satisfaction and out-of-pocket costs after thromboprophylaxis with aspirin versus low-molecular-weight heparin.

Methods: This study was a secondary analysis of the PREVENTion of CLots in Orthopaedic Trauma (PREVENT CLOT) trial, conducted at 21 trauma centers in the U.S. and Canada. We included adult patients with an operatively treated extremity fracture or a pelvic or acetabular fracture. Patients were randomly assigned to receive 30 mg of low-molecular-weight heparin (enoxaparin) twice daily or 81 mg of aspirin twice daily for thromboprophylaxis. The duration of the thromboprophylaxis, including post-discharge prescription, was based on hospital protocols. The study outcomes included patient satisfaction with and out-of-pocket costs for their thromboprophylactic medication measured on ordinal scales.

Results: The trial enrolled 12,211 patients (mean age and standard deviation [SD], 45 ± 18 years; 62% male), 9725 of whom completed the question regarding their satisfaction with the medication and 6723 of whom reported their out-of-pocket costs. The odds of greater satisfaction were 2.6 times higher for patients assigned to aspirin than those assigned to low-molecular-weight heparin (odds ratio [OR]: 2.59; 95% confidence interval [CI]: 2.39 to 2.80; p < 0.001). Overall, the odds of incurring any out-of-pocket costs for thromboprophylaxis medication were 51% higher for patients assigned to aspirin compared with low-molecular-weight heparin (OR: 1.51; 95% CI: 1.37 to 1.66; p < 0.001). However, patients assigned to aspirin had substantially lower odds of out-of-pocket costs of at least $25 (OR: 0.15; 95% CI: 0.12 to 0.18; p < 0.001).

Conclusions: Use of aspirin substantially improved patients' satisfaction with their medication after orthopaedic trauma. While aspirin use increased the odds of incurring any out-of-pocket costs, it protected against costs of ≥$25, potentially improving health equity for thromboprophylaxis.

Level of evidence: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.