Research priorities for pediatric venous thromboembolism prevention: communication from the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis

BACKGROUND: The incidence of pediatric venous thromboembolism (VTE) is increasing, and research is needed to determine safe and effective thromboprophylaxis strategies. OBJECTIVES: To identify and prioritize key research gaps in pediatric VTE. METHODS: The VTE Risk Factors and Thromboprophylaxis Working Party of the Pediatric and Neonatal Thrombosis and Hemostasis Subcommittee of the International Society on Thrombosis and Haemostasis (ISTH) Scientific and Standardization Committee conducted a crowdsourcing initiative during the 2023 and 2024 ISTH Congresses and via email listservs through the Children's Healthcare Advancements in Thrombosis Consortium and the Venous thromboEmbolism Network U.S. (VENUS) pediatric subgroup. Respondents identified priority research questions, which were then thematically grouped, ranked, and reviewed against current and ongoing research to define future research needs. RESULTS: Research questions were categorized into 4 themes: 1) risk factor identification and stratification, 2) advancements in risk assessment models and biomarkers, 3) optimal thromboprophylaxis approaches, and 4) implementation and practice integration. While risk assessment models and select randomized trials have informed prophylaxis for specific pediatric subgroups, evidence gaps remain, particularly for populations excluded from prior studies. Critical unanswered questions include the role of immobility, the value of mechanical prophylaxis, optimal anticoagulant selection, dosing and duration, and strategies for integrating risk-based prophylaxis across diverse care settings. CONCLUSION: This initiative defines consensus-driven research priorities for pediatric VTE prevention that, when addressed, will support the development of evidence-based clinical practice guidelines.