Elevated plasma factor VIII levels--a novel risk factor for venous thromboembolism

Area of Science:

• Hematology
• Thrombosis Research
• Vascular Medicine

Background:

• A link between high Factor VIII:C (FVIII:C) plasma levels and arterial thrombosis has been known for two decades.
• Recent research suggests elevated FVIII:C may also play a role in venous thromboembolic disease.

Purpose of the Study:

• To investigate the association between elevated FVIII:C levels and venous thromboembolism.
• To determine if elevated FVIII:C is an independent risk factor for venous thrombosis and recurrent events.

Main Methods:

• Analysis of plasma FVIII:C levels in patients following venous thrombosis.
• Multivariate analysis using data from the Leiden thrombophilia study.
• Prospective follow-up of patients with varying FVIII:C levels.

Main Results:

• 25% of patients exhibited FVIII:C levels over 1500 IU/l six months post-venous thrombosis, unrelated to acute phase reactions.
• Elevated FVIII:C levels were sustained for years and identified as an independent risk factor for venous thromboembolism.
• Individuals with FVIII:C > 1500 IU/l had a six-fold increased risk of venous thrombosis compared to those with FVIII:C < 1000 IU/l.
• High FVIII:C levels correlated with an increased risk of recurrent venous thrombosis.

Conclusions:

• Elevated plasma FVIII:C levels indicate a persistent, constitutional prothrombotic tendency.
• High FVIII:C is a significant independent risk factor for both initial and recurrent venous thromboembolic events.
• The underlying mechanism causing elevated FVIII:C levels requires further investigation.