PB0289 - Association of elevated coagulation factors VIII, IX and XI with recurrent thrombotic events in children with non-central venous line deep vein thrombosis

Background: The role of coagulation factors VIII (FVIII), FIX, and FXI for the prediction of recurrent venous thrombotic events (VTE) in children after a first non-central venous catheter (non-CVC) related deep vein thrombosis (DVT) remains unclear.

Aims: To investigate the association between FVIII/FIX/FXI and recurrent VTE in children with non-CVC DVT.

Methods: Children aged 0-18 years diagnosed with a first non-CVC DVT between 1993-2020 were included in this single-center retrospective cohort study. The primary outcome was recurrent VTE per ISTH definitions. FVIII/FIX/FXI were measured ≥30 days after the acute VTE. In multivariable logistic regression, the association between FVIII/FIX/FXI as continuous variables and VTE recurrence was investigated, adjusting for underlying conditions with chronic inflammation (lupus, antiphospholipid syndrome, vasculitis, and inflammatory bowel disease). The role of thrombophilia (minor/major/none) and of persistent/transient/no FVIII elevation were investigated in exploratory analyses. Ethics approval was obtained.

Results: In total, 98 patients were preliminarily included (1993-2014); median age at first DVT was 15.2 years (25th-75th percentile 12.6-16.6 years), 45% were male patients; 63% had lower extremity DVT; 23.5% patients had minor and 25.5% had major thrombophilia.
Median follow-up time was 2.2 years (25th-75th percentile 1.1-4.3 years). In total, 24/98 (24.5%) patients had a first recurrent VTE at a median of 203 days (25th-75th percentile 53-559 days). The most common type of recurrence was ipsilateral DVT (67%), 33% VTEs recurred at a new site.
There was no significant difference in FVIII/FIX/FXI levels according to presence/absence of VTE recurrence (Figure 1). In multivariable analysis (Table 1), there was no significant association between FVIII/FIX/FXI and VTE recurrence; chronic inflammation was a statistically significant predictor for recurrence in all three models. Exploratory analyses did not change the results.

Conclusion(s): The results suggest that FVIII/FIX/FXI may not be helpful to predict paediatric recurrent VTE. In contrast, having chronic inflammation increased recurrence risk in this cohort.