High prevalence of thrombophilic traits in children with family history of thromboembolism

Objectives: To determine a proximate family history of venous thromboembolism (VTE) in (1) the prevalence of thrombophilia; (2) the frequency of recommended changes in management resulting from thrombophilia evaluation; and (3) outcomes in longitudinal follow-up. Study design: Laboratory thrombophilia investigation was performed in 56 children with first- or second-degree family history of thromboembolism before age 55 years, but without personal history of thromboembolism, who were enrolled in a prospective inception cohort. VTE risk factors, family history, thrombophilia findings, and management recommendations were systematically collected, along with thromboembolism risk episodes/exposures, prophylactic anticoagulation, major bleeds, and thromboembolism events during follow-up. Results: The frequencies of all thrombophilia traits were higher than the general population. Among 32 children who underwent complete laboratory evaluation, 34% had ≥2 traits. Thrombophilia testing led to recommendations for risk-based transient antithrombotic prophylaxis in 71% of subjects. No thromboembolism episodes developed during more than 900 patient-months of follow-up, although at-risk exposures were infrequent. Conclusion: Risk-stratified approaches to primary prevention of pediatric VTE should be further evaluated in cooperative prospective studies.