Factors of Risk in the Development of Coronary Heart Disease (Framingham Heart Study)

By the 1940s cardiovascular disease was the leading cause of death in the United States, yet cardiology had almost no way to predict who would develop it. The U.S. Public Health Service designed it to find the factors predisposing to coronary disease in an ordinary population. The Framingham Heart Study began in 1948 and recruited 5,209 residents of Framingham, Massachusetts, aged 28 to 62, between 1948 and 1952. More than half were women, unusual for the epidemiological studies of the time.

William Kannel, who led the analytic work on the first major outcome report, and Thomas Dawber, who had directed the study since April 1950, published their six-year findings in Annals of Internal Medicine in 1961. The paper showed that high blood pressure, elevated serum cholesterol and electrocardiogram abnormalities each predicted coronary disease. Cigarette smoking had been linked to heart disease in a Framingham report the year before. The 1961 paper brought the phrase 'risk factor' into medical use to describe these measurable antecedents, giving clinicians a new vocabulary.

The reception was not uniformly enthusiastic. Many physicians doubted the epidemiological approach itself: in 1961 there was resistance to creating a Council on Epidemiology at the American Heart Association, and critics questioned whether Framingham residents represented Americans in general. The role of dietary fat and cholesterol was also disputed; Ancel Keys, who had described high cholesterol in coronary patients, was its best-known advocate.

The risk-factor idea soon became arithmetic. In 1967 Truett, Cornfield and Kannel combined seven factors in one model and found a 30-fold (men) to 70-fold (women) difference in coronary incidence between the highest and lowest tenths of risk. The study itself nearly closed: in 1969 the NIH ordered it phased out, private donors and President Nixon kept it alive, and from 1971 it ran under a federal contract with Boston University.

The cohort itself expanded over time, enrolling the children of the original participants in 1971 and a grandchildren cohort in 2002. In 1977 Framingham investigators reported that higher HDL cholesterol went with less coronary disease, and William Castelli, the fourth director, reported with colleagues in 1983 that weight gain raised cardiovascular risk. From 1976 Framingham risk profiles let physicians calculate an individual patient's predicted risk of a cardiovascular event.