A prospective study of venous thromboembolism in relation to factor V Leiden and related factors.
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
Aaron R
AR
Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis 55454, USA. folsom@epi.umn.edu
Cushman
Mary
M
Tsai
Michael Y
MY
Aleksic
Nena
N
Heckbert
Susan R
SR
Boland
Lori L
LL
Tsai
Albert W
AW
Yanez
N David
ND
Rosamond
Wayne D
WD
D020016:Activated Protein C Resistance; D000368:Aged; D015331:Cohort Studies; D005165:Factor V / Q000032:analysis*; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D044469:Racial Groups; D012307:Risk Factors; D013923:Thromboembolism / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D020246:Venous Thrombosis / Q000097:blood / Q000453:epidemiology / Q000209:etiology*
C095381:factor V Leiden; D005165:Factor V