Effect of Aspirin Versus Low-Molecular-Weight Heparin for Thromboprophylaxis in High-Risk and Fracture Location Subpopulations: A Secondary Analysis of the PREVENT CLOT Trial.

Authors

Sandip P Tarpada, Nathan N O'Hara, Deborah M Stein, Anthony J DeSantis, Renan C Castillo, Katherine P Frey, Gerard P Slobogean, I Leah Gitajn, Greg E Gaski, Laurence B Kempton, Conor P Kleweno, Reza Firoozabadi, Joseph Cuschieri, A Britton Christmas, Jeffery A Claridge, Debra Marvel, Robert V O'Toole, METRC

Published in

Journal of orthopaedic trauma. Oct 06, 2025. Epub Oct 06, 2025.

Abstract

To compare the effectiveness and safety of aspirin versus low-molecular-weight heparin (LMWH) for thromboprophylaxis in 11 high-risk or fracture location subpopulations.
Design: A post-hoc secondary analysis of the published PREVENT CLOT trial.
21 trauma centers.
Adult patients with an operatively treated extremity fracture or any pelvic or acetabular fracture were enrolled from April 2017 through August 2021. Patients with only hand or foot fractures, presenting >48 hours after injury, or with a history of VTE within 6 months of injury were excluded. The 11 subpopulations included i) a head injury, ii) an abdominal injury, iii) a spinal injury, iv) a thoracic injury, v) multiply injured patients, vi) obesity, vii) previous VTE ≥ 6 months, viii) isolated upper extremity fracture, ix) isolated lower extremity fracture, x) isolated pelvic or acetabular fracture, and xi) geriatric femur fracture.
The primary outcome was 90-day all-cause mortality. Secondary outcomes included non-fatal pulmonary embolism, proximal deep vein thrombosis (DVT), distal DVT, and bleeding events. Outcomes were assessed using Kaplan-Meier estimators and Cox proportional hazards models comparing 81 mg of aspirin versus 30 mg of LMWH twice daily. The threshold for statistical significance was a Bonferroni-corrected alpha of 0.001 to account for multiple comparisons.
The largest subpopulations were isolated lower extremity fractures (n=6,289), obesity (n=4,234), and polytrauma with Injury Severity Score (ISS) >16 (n=1,596). No comparison of aspirin vs LMWH within the 11 subpopulations for the 5 outcomes reached the corrected threshold for statistical significance of P < 0.001. However, 5 comparisons of aspirin vs LMWH were less than the conventional P-value of 0.05. Specifically, the aspirin group demonstrated lower mortality in patients with a head injury (difference, -3.2%; 95% CI -6.1% to -0.3%; P = 0.03) or a spine injury (difference, -6.0%; 95% CI -11.7% to -0.3%; P = 0.04) than the LMWH group. The LMWH group demonstrated a lower rate of distal DVTs for patients with a head injury (difference, 4.4%; 95% CI, 0.8% to 8.1%; P = 0.03), thoracic injury (difference, 1.5%; 95% CI, 0.0% to 2.9%; P=0.034) or with ISS >16 (difference, 1.7%; 95% CI, 0.2% to 3.3; P = 0.03) than the aspirin group.
Within 11 high-risk or fracture location-specific subpopulations, there were no statistically significant differences between aspirin or LMWH in the 90-day rates of all-cause mortality, non-fatal PE, proximal DVT, distal DVT, or bleeding complications at a threshold corrected for multiple comparisons (P < 0.001).
Therapeutic Level I.

PMID:
41056444
Bibliographic data and abstract were imported from PubMed on 08 Oct 2025.

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