Clot Chronicles: Thrombosis in Hospitalized Pediatric Patients with COVID-19 and MIS-C

Hello, I’m Emily Drake. I’m a nurse practitioner in the thrombosis and anticoagulation program at Boston Children’s Hospital. Today, on Clot Chronicles, I’m going to discuss the recent publication on the rate of thrombosis in children and adolescents hospitalized with COVID-19 or multisystem inflammatory syndrome (MIS-C) published in Blood in July of 2021. 

This study was a large multicenter, retrospective cohort study to determine the incidence of thrombosis in children hospitalized with COVID-19 or MIS-C, and to determine the associated risk factors in a total of 853 admissions in 814 patients between March 1, 2020, and August 15, 2020. Patients included in this study were divided into 3 subgroups for analysis: COVID-19, MIS-C, and asymptomatic COVID-19. 

The first key observation in this study was that the patients with MIS-C had the highest incidence of thrombosis at 6.5%. Patients with COVID-19 had the next highest incidence at 2.1%, and patients with asymptomatic COVID-19 had the lowest incidence of thrombosis at 0.7%. In putting these rates into perspective, the authors point out that the rate of venous thromboembolism (VTE) in children admitted to US tertiary care hospitals in 2007 was estimated to be at 0.58%. 

Another key observation from the study was that the incidence of mortality was 2.3% in hospitalized children with COVID-19 or MIS-C but was significantly higher at 28% in children and adolescents with MIS-C or COVID-19 who developed thrombosis. A third important observation from this study was that risk factors significantly associated with thrombosis were age (12 years of age or older), a cancer diagnosis, the presence of central venous catheters, and a diagnosis of MIS-C. 

Additionally, a D-dimer of greater than 5 times the upper limit of normal was significantly associated with thromboembolism in the study, a similar finding to multiple studies of adult patients with COVID-19. Another interesting finding from this study was that more than two-thirds of thromboembolism that occurred in hospitalized children with COVID-19 or MIS-C occurred in patients receiving thromboprophylaxis. This raised concerns and questions about optimal thromboprophylaxis for patients admitted to hospitals with COVID-19 or MIS-C, e.g., in what patient populations thromboprophylaxis should be considered, and additionally, what degree of thromboprophylaxis should be administered. 

Thank you very much, and I hope you enjoyed this review of VTE incidence in children and adolescents hospitalized with COVID-19 or MIS-C. 

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