Epidemiology and pathology of coronary artery disease: I. Method of study (original) (raw)

1960, Journal of Chronic Diseases

*Since 1954, when these matters were under consideration. two groups of investigators have succeeded in producing myocardial infarcts in animals: (I) Myasnikov. employing cholesterol feeding and physical strew2 and (2) Thomas and Hartroft using high fat diets plus chemical additives.3 504 Volume 12 Number 5 EPIDEMIOLOGY OF CORONARY ARTERY DISEASE I SOS the disease when myocardial damage was present, atherosclerosis in the coronar). arteries usually escaped his detection; and (3) the complete disease process had not been satisfactorily reproduced in animals. Considering this set of circumstances, the group reached several tentative conclusions. First, an epidemiologic study appeared justified, since (a) the disease was of high incidence and thus warranted a population approach, and (b) a study of its ecology, the primary concern of epidemiologists, might reveal that it was associated with certain characteristics or activities in a manner suggesting a causal relationship. Second, an approach appeared promising in which attention would he tlirected toward coronary artery atherosclerosis in its varying degrees of severityin relation to degree of exposure to epidemiologic variables, an approach that would require cooperative study by the pathologist and the epidemiologist. This method would have the major advantage of bringing a large portion of the spectrum of the disease under study, presumably ranging from little or no involvement of the coronary arteries to severe arterial disease and myocardial complications. Such an approach would necessarily be based upon the assumption that coronar>r arter!. atherosclerosis plays a major part in the etiology of coronar\. heart disease. Data from this study bearing upon this assumption are presented in a later section. A study design that would bring into focus the full range of gradations of atherosclerosis would make it possible to identify individuals in whom the disease was clearly absent. According to the evidence of necropsy studies,4,5 individuals without atherosclerosis* are generally believed to constitute a small minorit) among middle-aged and elderly males. If such "noncase" individuals were identified and utilized as a control group, presumably they would contrast more sharpl;, with severe "cases" in terms of etiological factors than would a clinically selected "noncase" group in which a large proportion of individuals with diseased arteries would necessarily be included. In this design, the "case" group would be composed of individuals with gradations of coronary artery atherosclerosis from subclinical stages to clinically manifest disease. "Noncases" have been particularly elusive as subjects for study in that they are not only apparently relatively rare among older males, but are also not clearly identifiable clinically. It appeared especiall!desirable, therefore, to identify these "noncases" with precision so that differences between cases and controls, in epidemiologic attributes, would stand out more BEADENKOPF ET AL.