Origins and early development of the case-control study

Summary

This paper traces the origins and early development of the case-control study, focusing on its evolution in the 19^th and early 20^th century. As with other forms of clinical investigation, the case-control study emerged from practices that originally belonged to the realm of patient care. This form of disease investigation can be viewed as the knitting together of medical concepts (caseness, disease etiology, and a focus on the individual) — and medical procedures (anamnesis, grouping of cases into series; and comparisons of the diseased and the healthy) — that are of ancient origin, but which were seldom brought together until the 20^th century. The analytic form of the case-control study can be found in 19^th century medical literature, but did not appear to be viewed as a special or distinct methodology. A number of clinical investigations, and several sociological studies, in the first half of this century can be described as case-control studies. The first modern case-control study was Janet Lane-Claypon’s study of breast cancer in 1926, but the design was used only sporadically in medicine and the social sciences until 1950, when four published case-control studies linked smoking and lung cancer. These 1950 studies synthesized the essential elements of the case-control comparison, produced a conceptual shift within epidemiology, and laid the foundation for the rapid development of the case-control design in the subsequent half century.

“Judging from the manner in which the subject is usually handled, the study of the etiology of diseases is generally undertaken with great levity, even by men of high acquirement. Some slight general knowledge, supported by a little more or a little less common sense, is quite sufficient to fit its possessor for the discovery of the causes of disease, in other words, to qualify him for the most complicated problem within the whole range of pathology.” (Louis, 1844: 487).