Established Risk Factors and Coronary Artery Disease: The Framingham Study

Long-standing risk factors for the development of coronary artery disease (CAD) have typically included age, blood levels of total and high-density lipoprotein (HDL) cholesterol, blood pressure, cigarette use, diabetes mellitus, and left ventricular hypertrophy on electrocardiography. Each of the traditional risk-factor measures has expanded in scope over time; for instance, systolic and diastolic blood pressure levels are each associated with the occurrence of CAD, and an individual need not be hypertensive to be at an increased risk. Although total (or low-density lipoprotein cholesterol) and HDL cholesterol are highly associated with CAD incidence, other newer lipid measures such as apolipoproteins A-I and B, and genetic markers have shown little or no additional effect in predicting CAD. Diabetes mellitus has been consistently associated with CAD but less data are available to demonstrate independent roles for obesity and regional adiposity. Although reports are more recent, hematologic factors such as fibrinogen concentration and leukocyte count have been consistently associated with CAD in observational studies. Prediction equations continue to emphasize the traditional biological factors and not behaviors. Among life-style habits such as diet, sedentary activity, and cigarette smoking, only the latter has been consistently used in CAD prediction because of its independent effect.