@article {1115,
	title = {Coagulation factors IX through XIII and the risk of future venous thrombosis: the Longitudinal Investigation of Thromboembolism Etiology.},
	journal = {Blood},
	volume = {114},
	year = {2009},
	month = {2009 Oct 01},
	pages = {2878-83},
	abstract = {<p>Higher levels of procoagulant factors and factor XII deficiency may be risk factors for first venous thromboembolism (VTE). We studied associations of coagulation factors IX through XIII with risk of future VTE in 2 general population samples. Using a nested case-control study combining the 21 860 participants of the Atherosclerosis Risk in Communities study and the Cardiovascular Health Study, we determined antigenic levels of these coagulation factors in primarily pre-event blood samples from 462 participants who subsequently developed VTE and 1047 participants who remained free of VTE. Only elevated levels of factors IX and XI were associated with increased risk of VTE after adjustment for age, sex, race, and study. For factor IX, the odds ratio (OR) was 1.4 (95\% confidence interval [CI], 1.0-2.0) comparing the top to bottom quintile. The OR for factor XI was higher: 2.0 (95\% CI, 1.4-2.9). With further adjustment for body mass index and diabetes, only elevated factor XI remained associated with VTE risk: OR 1.8 (95\% CI, 1.3-2.7). Associations were similar by study and whether the thrombosis was idiopathic or secondary. Factor XII deficiency was not related to VTE risk. Among these procoagulant factors, only elevated factor XI was a risk factor for VTE.</p>},
	keywords = {Aged, Aged, 80 and over, Case-Control Studies, Factor IX, Factor X, Factor XI, Factor XII, Factor XIII, Female, Humans, Longitudinal Studies, Male, Middle Aged, Odds Ratio, Prospective Studies, Risk Factors, Venous Thromboembolism},
	issn = {1528-0020},
	doi = {10.1182/blood-2009-05-219915},
	author = {Cushman, Mary and O{\textquoteright}Meara, Ellen S and Folsom, Aaron R and Heckbert, Susan R}
}
@article {6930,
	title = {Prospective study of circulating factor XI and incident venous thromboembolism: The Longitudinal Investigation of Thromboembolism Etiology (LITE).},
	journal = {Am J Hematol},
	volume = {90},
	year = {2015},
	month = {2015 Nov},
	pages = {1047-51},
	abstract = {<p>Elevated plasma concentrations of coagulation factor XI may increase risk of venous thromboembolism (VTE), but prospective data are limited. We studied prospectively the associations of plasma factor XI and a key F11 genetic variant with incident VTE in whites and African-Americans. We measured factor XI in 16,299 participants, initially free of VTE, in two prospective population cohorts. We also measured the F11 single nucleotide polymorphism rs4241824, which a genome-wide association study had linked to factor XI concentration. During follow-up, we identified 606 VTEs. The age, race, sex, and study-adjusted hazard ratio of VTE increased across factor XI quintiles (P < 0.001 for trend), and the hazard ratio was 1.51 (95\% CI 1.16, 1.97) for the highest versus lowest quintile overall, and was 1.42 (95\% CI 1.03, 1.95) in whites and 1.72 (95\% CI 1.08, 2.73) in African-Americans. In whites, the F11 variant was associated with both factor XI concentration and VTE incidence (1.15-fold greater incidence of VTE per risk allele). In African-Americans, these associations were absent. In conclusion, this cohort study documented that an elevated plasma factor XI concentration is a risk factor for VTE over extended follow-up, not only in whites but also in African-Americans. In whites, the association of the F11 genetic variant with VTE suggests a causal relation, but we did not observe this genetic relation in African-Americans.</p>},
	keywords = {African Americans, Aged, Alleles, European Continental Ancestry Group, Factor XI, Female, Gene Expression, Humans, Incidence, Longitudinal Studies, Male, Middle Aged, Polymorphism, Single Nucleotide, Proportional Hazards Models, Prospective Studies, Risk Factors, United States, Venous Thromboembolism},
	issn = {1096-8652},
	doi = {10.1002/ajh.24168},
	author = {Folsom, Aaron R and Tang, Weihong and Roetker, Nicholas S and Heckbert, Susan R and Cushman, Mary and Pankow, James S}
}
