Waiting to initiate venous thromboembolism prophylaxis increases the incidence of venous thromboembolism in pediatric patients with traumatic bleeding.

Background: We aim to evaluate the relationship between timing of venous thromboembolism (VTE) prophylaxis initiation and incidence of VTE in a high-risk cohort of injured children.

Methods: This is a retrospective analysis of the Acute Care Surgery Trauma Quality Improvement Program database (2020-2022). Injured children (younger than 18 years) who received blood products or underwent hemorrhage control surgery within 4 hours of arrival were included. The primary outcome was VTE (deep venous thrombosis or pulmonary embolism). Multivariable analysis assessed the relationship between timing of VTE prophylaxis and VTE, adjusting for prophylaxis agent, type of surgery, head injury severity, interfacility transfer, total 4-hour blood product administration, injury mechanism, Injury Severity Score, age, sex, and trauma center level, clustered by facility. Missing data were imputed. Subgroup analyses include age younger than 15 years.

Results: Of 4,575 children included, 3,902 underwent hemorrhage control surgery, and 4,141 received blood product transfusion. In total, 185 (4%) developed VTE (n = 154 deep venous thrombosis and/or n = 45 pulmonary embolism). The VTE cohort was older (16 [15-17] vs. 16 [13-17] years), had higher Injury Severity Score (27 [19-36] vs. 25 [14-35]), and was more likely to be in shock on arrival based on shock index, pediatric age-adjusted score (75% vs. 64%). The rate of prophylaxis was 51%, with common agents being low-molecular-weight heparin (38%) and unfractionated heparin (11%). The median (interquartile range) time to initiation of prophylaxis was 2 (2-4) days. In the multivariable analysis, every 1-day delay to initiation of VTE prophylaxis was associated with 6% increase in odds of VTE (odds ratio [95% confidence interval], 1.06 [1.03-1.10]; p < 0.001). In a subset of children younger than 15 years with VTE incidence of 3%, this relationship persisted (every 1-day delay = 4% increase in odds of VTE; odds ratio, 1.04 [1.01-1.07]; p = 0.04).

Conclusion: Earlier VTE prophylaxis initiation was associated with decreased odds of VTE development in this high-risk pediatric cohort, highlighting opportunities to optimize VTE prevention. Future multicenter studies regarding safety and therapeutic agent of choice are required.

Level of evidence: Therapeutic/Care Management; Level III.