Objective

To determine the importance of antithrombin [AT] deficiency as risk factor or predictor for fatal/non-fatal recurrent venous thromboembolism (VTE) in children.

Methods

In the present cohort of 874 consecutively enrolled pediatric patients with VTE aged newborn to <18 years the rate of VTE recurrence and the time to recurrence in relation to AT-deficiency [confirmed by underlying gene mutations; type 1 deficiency n=17; type 2 deficiency n=3], age and sex was determined. Twenty of 874 patients [2.4%] suffered from AT-deficiency. From the same cohort 150 VTE children carrying the heterozygous F5 G1691A mutation [F5: 17.7%] served as controls. Patients were prospectively followed for a median of 84 months. Data were pooled across participating sites to increase power and to enhance the generalisability of the data. Incidence rates were given as events per 1000 person-years.

Results

Of the 170 children enrolled 26 [AT n=9; F5 n=17] had recurrent VTE at a median of 15 months [95%CI: 12-36] following VTE onset: two of nine [AT] and two of 17 [F5] children suffered recurrent VTE while on anticoagulation with warfarin. The overall incidence rate of recurrence was 61.5 in patients with AT-deficiency compared to 23.5 for pediatric F5 carriers [p=0.02]. The recurrent-free survival probability is shown in the figure [logrank p-value: p=0.001]. When comparing AT patients and F5 children multivariate analysis [Cox regression] adjusted for age, sex and duration of anticoagulation treatment showed that AT deficiency [HR/95%CI: 4.1/1.8-9.4] significantly influenced the hazard for recurrent VTE.

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Conclusions

Based on multivariate analysis, the presence of AT deficiency was associated with an increased risk of VTE recurrence. AT-deficiency in pediatric patients should be identified at VTE onset and the possible influence of intensified treatment protocols on recurrence should be studied in future prospective international studies.

Condensed abstract

To determine the relative importance of antithrombin deficiency or factor V (FV) mutations as risk factors for fatal/non-fatal recurrence in pediatric thromboembolism (VTE). Antithrombin deficiency influenced the hazard for recurrent VTE.

Disclosures:

No relevant conflicts of interest to declare.

Topics:
antithrombin iii deficiency, child, venous thromboembolism, anticoagulation, antithrombin iii, antithrombins, factor v, thromboembolism, warfarin, cox proportional hazards models

Author notes

*

Asterisk with author names denotes non-ASH members.

This icon denotes a clinically relevant abstract

© 2013 by The American Society of Hematology
2013
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