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.