The growing demand for preventive measures for coronary heart disease led to greater use of statistical correlations that related personal characteristics to future mortality rates. This model was applied most successfully in the renowned Framingham Heart Study, a unique long-term epidemiological community study. The Framingham study introduced the life insurance risk factor into research in medicine and public health, but restricted its scope by excluding the many social factors used by the life insurance industry.

As coronary heart disease reached epidemic proportions in the late 1940s, epidemiological studies were undertaken to better understand the etiology of the disease. Most of the studies examined workers in specific occupations or firms, including the Minnesota Business and Professional Men's study, the Albany Cardiovascular Health Study of New York State civil servants, the Chicago Peoples Gas Company study, the Tecumseh (Michigan) Health Study, and the Chicago Western Electric Company study. All used a methodology that had been devised in the late nineteenth century by the life insurance industry: they gave medical examinations to a sample of persons who were free of coronary heart disease and followed them for a number of years to determine the personal characteristics that were associated with higher rates of the disease.

In 1947 the U.S. Public Health Service undertook planning for the Framingham (Massachusetts) Heart Study as a community epidemiological study and in 1949 assigned it to the newly created National Heart Institute of the National Institutes of Health. The unique feature of the Framingham Heart Study was that physicians repeated the medical examinations of participants every two years. The follow-up examinations provided information about illnesses and changes in medical conditions and personal behaviors since the previous examination. The examinations also provided accurate information on all manifestations of coronary heart disease, not just deaths or myocardial infarctions. Study physicians provided no medical care to the participants, except in emergencies, but referred them to their regular sources of care.