A New Type of Observational Epidemiology

Abstract

Around 1950 a new type of epidemiological study was invented, the prospective or cohort study, in which people at moderate risk of a disease are examined and answer questions about lifestyle. They are then observed for 5, 10 or more years. Incidence of disease can then be related back to aspects of lifestyle (including diet) and to findings at the initial medical examination. Those who develop the disease of interest had been questioned and examined in exactly the same way as those who do not. The first prospective study of CHD was conducted in the town of Framingham, Massachusetts, USA. Here, and in other prospective studies that followed, the big three factors predicting risk of CHD have been raised serum cholesterol, blood pressure and cigarette smoking. Years 1949–1968.