An Intuitive Approach to Understanding the Attributable Fraction of Disease Due to a Risk Factor: The Case of Smoking

The health damage from tobacco use has been studied intensively, yet quantifying the precise burden of disease and death due to smoking is a complex problem, and consequently open to manipulation by interested parties. The goals of this paper are to clearly communicate the concept of the attributable fraction (AF), i.e., the proportion of disease in a population which can be attributed to a risk factor, and to understand the relationship between the AF, the prevalence of exposure in a population, and the relative risk of disease given the exposure. The current approach to calculating the AF is summarized. An intuitive formula is proposed, with accompanying graphical illumination. For diseases caused by smoking, the AF of disease due to smoking increases with the prevalence of smoking and with the relative risk of disease due to smoking. The proposed method has the potential to help health professionals and decision makers understand the concept of the burden of disease due to smoking or other lifestyle, environmental, and occupational factors, in the context of public health importance. This will aid sound decision-making in public health policy.