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?

https://arctichealth.org/en/permalink/ahliterature174852
Source
Thromb Haemost. 2005 May;93(5):842-6
Publication Type
Article
Date
May-2005
Author
Philip S Wells
Nicole J Langlois
Marc A Webster
James Jaffey
Josdalyne A Anderson
Author Affiliation
Department of Medicine, University of Ottawa, Ontario, Canada. pwells@ohri.ca
Source
Thromb Haemost. 2005 May;93(5):842-6
Date
May-2005
Language
English
Publication Type
Article
Keywords
Adult
Aged
Canada
Case-Control Studies
Factor VIII - biosynthesis - chemistry
Female
Hematology - standards
Humans
Male
Middle Aged
Odds Ratio
ROC Curve
Reference Values
Regression Analysis
Risk factors
Sensitivity and specificity
Thromboembolism - blood - diagnosis
Venous Thrombosis - blood - diagnosis
Abstract
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. Factor VIII levels were measured and compared between cases and controls. The optimal cut-off value to designate factor VIII levels as elevated was determined using a variety of methods. The optimal upper cut-off value for factor VIII levels was 270 IU/dl. In the logistic regression analysis, cases were more likely to have elevated factor VIII levels (OR:8.76), as were females (OR:1.93) and older subjects (OR: 1.05). Factor VIII cutoffs for a 95% specificity by age were 238 IU/dl for subjects 70. Our findings confirm that elevated factor VIII is associated with an increased risk of idiopathic VTE. In our patients and matched controls, the current upper limit of normal (150 IU/dl) for factor VIII is not of clinical use. We propose that the upper limit be increased to 270 IU/dl or individual labs should establish their upper limit if they wish their assays to be discriminatory in patients with VTE. Age specific cut-offs may be clinically relevant.
PubMed ID
15886797 View in PubMed
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