Risk for Post Thrombotic Syndrome (PTS) Development in Children with Extremity Deep Venous Thrombosis (DVT): Results of the US Centers for Disease Control and Prevention (CDC) Pediatric Thrombosis and Hemostasis Centers.
Authors: Manco-Johnson Marilyn J. , Beckman Michele G. , Goldenberg Neil A. , Thornburg Courtney , Michaels Lisa A. , Pipe Steven W. , Moll Stephan , Rodriquez Vilmarie , Kulkarni Roshni 
Published: October 2019

Abstract
Abstract 4000
Poster Board III-936

Background
There is insufficient information regarding the epidemiology and outcomes of DVT in children. The CDC began a consented registry in August 2003 at eight pilot Centers for Thrombosis and Thrombophilia including six pediatric sites in order to assess the scope and severity of DVT morbidity in children.

Methods
Data for this analytic project were extracted from the CDC thrombosis registry. We performed a nested case-control study within the registry cohort. Children and adults are eligible to enroll onto this consented registry if they have a history of thrombosis, thrombophilia or a positive family history or either. DVT site, extent, recurrence and BMI were determined clinically. In addition, thrombophilia testing batteries, imaging protocols and determinations of PTS outcomes of DVT were made locally and criteria were not standardized among participating centers.

Results
As of March 2009 the CDC registry included 316 cases of DVT in infants and children (ages 0-21), and 2414 cases in adults (> 21). There were 16 cases reported to have lower extremity (LE) PTS in children and 184 in adults. Table 1 displays effects of thrombus site, recurrence and BMI on PTS prevalence. The proportion of LE DVT involving the inferior vena cava (IVC) was 5.5-fold higher in children compared to adults (11% vs 2%). Furthermore, among cases of IVC involvement, the prevalence of PTS following IVC thrombosis was remarkably higher in children compared with adults (38.9 vs 6.3%, P < 0.001). The prevalence of PTS following LE DVT overall in children did not differ from adults. Results for upper extremity DVT and resultant PTS were similar. Fifteen percent of children had recurrence. Increasing number of DVT events was associated with an increased risk of PTS. BMI was higher in children who developed PTS (p = 0.06; BMI > 28, OR 3.3 [1.08, 9.59]). In addition, thrombophilia was a risk factor for developing PTS in children (p = 0.02; OR = 2.9 [CI 1.03, 8.05]), with the highest risk determined with antiphospholipid syndrome (p = 0.02; OR = 3.4 [1.09, 9.93]) and protein C deficiency (p = 0.02, OR = 10.9 [0.84, 99.3]).

Discussion
Children with LE DVT demonstrate a high rate of IVC thrombosis, and a higher relative risk of PTS in cases of IVC involvement. Elevated BMI and thrombophilia augment the risk of PTS in children. The limitations of this study include the lack of standardization in DVT diagnostic and PTS evaluations. The study findings support application of standardized approaches to the diagnosis and follow-up evaluation of children with DVT in order to more meaningfully determine outcomes for future interventive trials.

Disclosures:
Moll: Ovation: Consultancy; GTC Biotherapeutics: Consultancy; Talecris: Consultancy.