Introduction:
Sickle cell disease (SCD) is the most common inherited hemoglobinopathy with an annual incidence of 300,000 to 400,000 live births worldwide.1 SCD is considered a prothrombotic state due to enhanced platelet function,2,3 impaired fibrinolysis4 and chronic activation of coagulation cascade with decreased levels of natural anticoagulants and increased pro-coagulant factor activation.5 All elements of Virchow’s triad- endothelial injury, vascular stasis, and hypercoagulability- are present in SCD, creating a highly thrombogenic state.6 Individuals with SCD are at increased risk for thromboembolism with estimates in adults ranging from 4-fold to 100-fold increase in risk.7 Most of the data regarding the risk of thrombosis in SCD pertains to adults8–10 and similar data regarding prevalence and risk factors for thrombosis in children with SCD is limited.
Over the past two decades, children’s hospitals in the United States have seen an alarming 200% increase in the rate of hospital-acquired thrombosis.11 In response, pediatric-specific venous thromboembolism (VTE) prophylaxis guidelines have been developed to prevent hospital-acquired venous thrombosis. However, these guidelines do not consider unique, disease-specific mechanisms that further increase the risks of VTE in SCD. This has resulted in wide variability of thromboprophylaxis practices across different institutions for hospitalized children with SCD.12
At Texas Children’s Hospital (TCH), our practice has been to prescribe thromboprophylaxis for patients with SCD who are 18 years of age and older admitted to the hospital or 16 years of age and older admitted to the intensive care unit (ICU). Over the past few years, we anecdotally observed an increase in the incidence of VTE events in younger children with SCD, prompting us to conduct this study. We hypothesized that the risk of VTE in SCD is higher in adolescents and in the setting of additional prothrombotic risk factors like intensive care unit (ICU) admission and presence of central venous catheter (CVC). Our objectives were to review our institutional cohort of subjects with SCD who had a hospital acquired VTE, describe their prothrombotic risk factors, and analyze treatment outcomes. Furthermore, we aimed to revise our institutional thromboprophylaxis guidelines, with the ultimate goals of reducing the rate of hospital-acquired thrombotic events and improving outcomes for this population.