Approaches to an epidemiology of health

A new definition of health and its relation to disease and illness is presented, and various approaches to epidemiological studies of health are discussed. The expanded definition reflects a major change in epidemiological thinking and practice. As the infectious diseases declined in the industrialized countries, it became increasingly clear that the noninfectious diseases were the most important causes of illness, disability, and death. Epidemiologists began to shift their efforts in this direction, and the chronic diseases have become the dominant field of epidemiological research in these countries. The new definition, however, no longer suffices, for the scope of epidemiological investigation has broadened beyond its boundaries. For one thing, the definition does not include trauma which, as a result of war and more limited forms of assault, as well as accidents and suicidal attempts, accounts for a considerable part of morbidity and mortality. Epidemiological studies of trauma, particularly that due to accidents and suicide, have been carried out in increasing numbers during the past several decades and need to be included in the conceptual framework of modern epidemiology. The purpose of this paper is to attempt to clarify the concepts and interrelations of health, illness, and disease; to demonstrate that the epidemiology of health is not a luxury or a minor concern but rather an area of crucial significance to the majority of the world's population; and to indicate the variety of approaches that have been used in its scientific pursuit. Much more can and will be done in the scientific development of an epidemiology of health. A precondition, however, is the casting off of the narrow viewpoints and constricting traditions which hinder interest and activity in this field.