Significance of Measurement
Fibrinogen has been shown to be strongly predictive of both mortality (Fried et al., 1998) and the onset of cardiovascular disease (Kannel et al., 1987; Patel et al., 1994, 1995; Ridker et al., 1997; Tracy et al., 1995). Fibrinogen is also as important as low levels of HDL cholesterol in predicting cardiovascular disease (de la Serna, 1994).

The relationship between SES and fibrinogen levels has been suggested as the mechanism linking low social status and stress to cardiovascular disease (Brunner et al., 1996; De Boever et al., 1995; Markowe et al., 1985; Wilson et al., 1993).

Method of Measurement
Measured using blood serum or plasma. The NHANES study measured fibrinogen concentration in plasma using the Clauss clotting method. This test method involves measuring the rate of fibrinogen to fibrin conversion in a diluted sample under the influence of excess thrombin. Since under these conditions the fibrinogen content is rate limiting, the clotting time can be used as a measure of the concentration of the fibrinogen and in fact, the clotting time is inversely proportional to the level of fibrinogen in the plasma(http://www.cdc.gov/nchs/data/nhanes/frequency/lab11doc.pdf).

References
· Brunner, E., Smith, G., Marmot, M., Canner, R., Beksinska, M., & O’Brien, J. (1996). Childhood social circumstances and psychosocial and behavioural factors as determinants of plasma fibrinogen. Lancet, 347, 1008-1013.
· De Boever, E., De Bacquer, D., Braeckman, L., Baele, G., Rosseneu, M., & De Backer, G. (1995). Relation of fibrinogen to lifestyles and to cardiovascular risk factors in a working population. International Journal of Epidemiology, 24(5), 915-921.
· de la Serna, G. (1994). Fibrinogen: A new major risk factor for cardiovascular disease: A review of the literature. Journal of Family Practice, 39, 468-477.
· Fried, L., Kronmal, R., Newman, A., Bild, D., Mittelmark, M., Polak, J., et al (1998). Risk factors for 5-year mortality in older adults: The Cardiovascular Health Study. Journal of American Medical Association, 279, 585-592.
· Kannel, W., Wolf, P., Castelli, W., & D’Agostino, R. (1987). Fibrinogen and risk of cardiovascular disease: The Framingham Study. Journal of American Medical Association, 258, 1183-1186.
· Markowe, H., Marmot, M., Shipley, M., Bulpitt, C., Meade, T., Stirling, Y., et al (1985). Fibrinogen: A possible link between social class and coronary heart disease. British Medical Journal, 291, 1312-1314.
· National Center for Health Statistics. (2002). NHANES 1999-2000 public data release file: Laboratory 11- C-reactive protein (CRP), fibrinogen, helicobacter pylori, bone alkaline phosphatase, and urinary N-teleopeptides. Retrieved March 28, 2005, from http://www.cdc.gov/nchs/data/nhanes/frequency/lab11doc.pdf
· Patel, P., Carrington, D., Strachan, D., Leatham, E., Goggin, P., Northfield, T., et al. (1994). Fibrinogen: A link between chronic infection and coronary heart disease. Lancet, 343(8913), 1634-1635.
· Patel, P., Mendall, M., Carrington, D., Strachan, D., Leatham, E., & Molineaux, N. (1995). Association of helicobacter pylori and chlamydia pneumonia infections with coronary heart disease and cardiovascular risk factors. British Medical Journal, 311, 711-714.
· Ridker, P., Cushman, M., Stampfer, M., Tracy, R., & Hennekens, C. (1997). Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men. New England Journal of Medicine, 336, 973-979.
· Tracy, R., Bovill, E., Yanez, D., Psaty, B., Fried, L., Heiss, G., et al. (1995). Fibrinogen and factor VIII, but not fact VII, are associated with measures of subclinical cardiovascular disease in the elderly: Results from the Cardiovascular Health Study. Arteriosclerosis, Thrombosis and Vascular Biology, 15, 1269-1279.
· Wilson, T., Kaplan, G., Kauhanen, J., Cohen, R., Wu, M., Salonen, R., et al. (1993). Association between plasma fibrinogen concentration and five socioeconomic indices in the Kuopio Ischemic Heart Disease Risk Factor Study. American Journal of Epidemiology, 137(3), 292-300.