The essential tension between absolute and relative causality

Epidemiologists can be viewed as risk sentinels who explore the possible health consequences of the changes in mass behaviors environmental exposures or societal changes. However some findings if not put in a proper context may have inadvertently harmful consequences on the public. The adverse consequence of the research on oral contraceptives in the mid-1990s is used to illustrate this point. Therefore epidemiologic studies should adopt measures to prevent misinterpretation and controversy that arise from reporting risk association without indicating the attributable disease burden. It is noted that epidemiologists use two types of causal inference namely the relative and absolute causality. Relative risks are a very handy tool for screening risk factors that do not require population data on prevalence while measures of attributable risk require direct or indirect population-based information. Such contrasting measurement of risks creates an `essential tension in epidemiologic research to discover risk factors and invent preventive strategies. Hence a thorough identification of causes is important to define the range of public health or clinical interventions capable of successful disease prevention.