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Profiling risk: the emergence of coronary heart disease epidemiology in the United States (1947-70).

This historical study examines the development of coronary heart disease (CHD) research and its role in the evolution of post-1945 chronic disease epidemiology in the United States. To give the examination greater salience, it compares the pathway represented by CHD epidemiology with that of lung cancer. Historians have paid less attention to the differences between the two, which later merged into what we now call 'risk factor epidemiology'. This study assesses why CHD epidemiology in the post-war period almost uniformly began with cohort studies and primarily stressed clinical variables as putative aetiological factors. It describes how CHD epidemiologists sought to justify the creation of a non-infectious chronic disease epidemiology, a position reinforced by the relative swiftness with which they obtained important results. It also follows the emergence of 'risk factor thinking' within CHD epidemiology. CHD epidemiology critically differed from its lung cancer counterpart in that it identified multiple factors of risk, each producing relatively small effects, rather than a single factor producing a strong and evident outcome. Consequently, it was difficult for CHD epidemiologists to demonstrate causality and to confirm scientifically that reducing risk factors would lower CHD rates. This had significant consequences for primary prevention and public health policy.