Elevated factor VIII is a risk factor for idiopathic venous thromboembolism in Canada - is it necessary to define a new upper reference range for factor VIII?

Previous studies suggest elevated factor VIII is a common, independent risk factor for venous thromboembolism (VTE); however, these studies included secondary and idiopathic VTE. We sought to explore the association between elevated factor VIII and VTE in Canadian patients with idiopathic thrombosis, and confirm the current upper factor VIII reference range was appropriate. We enrolled 300 consecutive patients with idiopathic VTE who were matched to friend controls by age, sex and ethnicity.