Racial Differences In Pediatric Venous Thromboembolism

Racial differences in the prevalence, risk factors, outcomes and recurrence rates of venous thromboembolism (VTE) have been reported in adults with the highest prevalence in African American (AA) males. Individuals of AA origin also have higher incidence of pulmonary embolism and increased mortality as compared to Caucasians. Such data are unknown in childhood VTE.

Our aim was to evaluate the racial differences in risk factors, treatment response, outcomes and risks for recurrence in childhood VTE at a single center.

All patients presenting to the pediatric hematology oncology service at this large urban Children's Hospital were followed prospectively from 2000–2010 and analyzed in a systematic manner. Data were analyzed using the SPSS v.17 software after approval from the institutional review board.

Preliminary analysis revealed that two hundred and eighteen patients with VTE were followed. There were 105 (48.2%) AA, 100 (45.9%) Caucasian (C), 4 (1.8 %) Middle Eastern (ME), 4(1.8%) Hispanic (H) and 5 Asian/Pacific islander (API) patients. Differences between AA and C were analyzed.

Of the AA patients, there were 52 females (F), 53 males (M); Sites of presentation were upper extremity (UE) 12, lower extremity (LE) 24, pulmonary embolism (PE) 25, cortical sinus thrombosis (CST) 5, jugular (J) 13, vena caval (VC) 10, hepatic (H) 2 and cardiac atrial (CA) 8. Thirty six patients had more than one site at presentation. Of the Caucasian patients, there 51 F and 49 M; Sites of presentation were UE 12, LE 25, PE 17, CST 16, H 3, CA 8, VC 9, jugular 7, renal 3. Twenty four patients had more than one site of presentation.

In AA patients, risk factors were persistently elevated D-Dimer and FVIII levels in 34 (32.4%) and 14 (13.3%) patients respectively; Elevated Lipoprotein (a){Lp(a)} in 24 (22.9%), positive cardiolipin antibodies (ACLA) in 11 (10.5%), ANA 18 (17.1%), and Lupus anticoagulant in 15 (14.3%) of patients. There were no patients with the Factor V Leiden (FVL) or the Prothrombin gene mutation. Clinical risk factors included the presence of central venous lines (CVL) in 58.1%, obesity in 26.7% and major surgery and immobilization in 36.2% and 30.5% respectively. Thirty percent of AA patients had positive family history of thrombosis in immediate family members.

In Caucasian patients, risk factors were persistently elevated D- Dimer and FVIII levels in 19 (19%) and 13 (13%); antithrombin III deficiency in 3 (3%), heterozygous FVL in 10 (10%) and the Prothrombin gene variant in 3 (3%); Positive ACLA in 8(8 %), ANA in 11 (11%) and LA in 4 (4%), Elevated Lp(a) in 11 (11%). Clinical risk factors included presence of central venous lines (CVL) in 44.1%, obesity in 22% and major surgery and immobilization in 31% each. Interestingly, 30% of Caucasian patients had a positive family history of thrombosis in immediate family members

In AA patients, 61.4% had complete (CR) or partial resolution (PR); in C patients 68.4% had CR or PR. Eleven (10%) AA and 7 (7%) C patients had recurrent events.

There were no statistically significant differences in gender, laboratory and clinical risk factors and outcomes between African American and Caucasian patients analyzed. As anticipated, the FVL and Prothrombin gene variants were not seen in AA patients.

In contrast to adults, there were no racial differences in presentation, risk factors and outcomes between Caucasian and African American patients with VTE followed at this single Children's Hospital thrombosis center. We believe this is the first report on racial differences in pediatric VTE. Larger population based studies are needed to confirm these findings.

No relevant conflicts of interest to declare.