Factor V Leiden was significantly associated with an increased risk of venous thromboembolism compared with noncarriers (OR 3.67; 95% CI 2.20-6.12).
Case-Control (n=1,023)
Yes
Do factor V-related risk factors (Factor V Leiden, HR2 haplotype, APC resistance, factor V antigen) increase the risk of venous thromboembolism in the general population?
Factor V Leiden and APC resistance are important risk factors for VTE in the general population, while HR2 haplotype and factor V antigen primarily increase risk when combined with factor V Leiden.
Effect estimate: OR 3.67 (95% CI 2.20-6.12)
The aim of this study was to examine the occurrence of venous thromboembolism (VTE) in relation to factor V-related risk factors. Using a nested case-control design combining 2 population-based prospective studies, we measured factor V Leiden, HR2 haplotype, activated protein C (APC) resistance, and plasma factor V antigen in 335 participants who developed VTE during 8 years of follow-up and 688 controls. The overall odds ratio (OR) of VTE was 3.67 (95% CI, 2.20-6.12) in participants carrying factor V Leiden compared with noncarriers. APC resistance measured after predilution with factor V-deficient plasma conferred an OR of 2.58 (95% CI, 1.62-4.10). All 3 participants homozygous for the HR2 haplotype had a VTE, and the OR of VTE for homozygosity was estimated to be 5.5 (95% CI, 2.45-12.5). Carriers of the HR2 haplotype otherwise were not at increased risk of VTE overall (OR = 1.05; 95% CI, 0.64-1.72), but double heterozygotes for HR2 and factor V Leiden carried an OR of idiopathic VTE of 16.3 (95% CI, 1.7-159) compared with noncarriers. Factor V antigen also was not associated with VTE overall, but for participants with the combination of high factor V antigen plus factor V Leiden the OR of idiopathic VTE was 11.5 (95% CI, 4.2-31.4). In the general population, APC resistance and factor V Leiden were important VTE risk factors; homozygosity for the HR2 haplotype may be a risk factor but was rare; otherwise, HR2 haplotype and factor V antigen were not risk factors except in carriers of factor V Leiden.
Folsom et al. (Mon,) conducted a case-control in Venous thromboembolism (VTE) (n=1,023). Factor V Leiden vs. Noncarriers was evaluated on Venous thromboembolism (VTE) (OR 3.67, 95% CI 2.20-6.12). Factor V Leiden was significantly associated with an increased risk of venous thromboembolism compared with noncarriers (OR 3.67; 95% CI 2.20-6.12).