When Is It Safe to Start VTE Prophylaxis after Blunt Solid Organ Injury? A Prospective AAST Multi-Institutional Trial

Abstract Background The optimal time to initiate venous thromboembolism (VTE) chemoprophylaxis (VTEp) after blunt solid organ injury remains controversial as VTE mitigation must be balanced against bleeding promulgation. Evidence from primarily small, retrospective, single-center work suggests VTEp ≤48 h is safe and effective. This study was undertaken to validate this clinical practice. Methods Blunt trauma patients presenting to 19 participating trauma centers in North America were screened over a one-year study period beginning between August 1 and October 1, 2021. Inclusions were age > 15 years; ≥1 liver, spleen, or kidney injury; and initial nonoperative management (NOM). Exclusions were transfers, ED death, pregnancy, and concomitant bleeding disorder/anticoagulation/antiplatelet medication. A priori power calculation stipulated the need for 1,158 patients. Time of VTEp initiation defined study groups: Early (≤48 h of admission) vs. Late (>48 h). Bivariate and multivariable analyses compared outcomes. Results In total, 1,173 patients satisfied study criteria with 571 (49%) liver, 557 (47%) spleen, and 277 (24%) kidney injuries. Median patient age was 34 [25-49] years and 67% (n = 780) were male. Median ISS was 22 [14-29] with AIS Abdomen 3 [2-3] and median AAST grade of solid organ injury 2 [2-3]. Early VTEp patients (n = 838, 74%) had significantly lower rates of VTE (n = 28, 3% vs. n = 21, 7%, p = 0.008); comparable rates of NOM failure (n = 21, 3% vs. n = 12, 4%, p = 0.228); and lower rates of post-VTEp blood transfusion (n = 145, 17% vs. n = 71, 23%, p = 0.024) when compared to Late VTEp patients (n = 301, 26%). Late VTEp was independently associated with VTE (OR 2.251, p = 0.046). Conclusion Early initiation of VTE chemoprophylaxis was associated with significantly reduced rates of VTE with no increase in bleeding complications. VTEp initiation ≤48 hours is therefore safe and effective and should be the standard of care for patients with blunt solid organ injury. Level of Evidence II, Therapeutic and Care Management