Commentary: What can epidemiology accomplish?

Abstract

Over the past 20 years epidemiological studies of risk factors have led the way to a great many discoveries useful to public health. Some particularly striking examples are found in child health. We can point to the prevention of Sudden Infant Death Syndrome by sleeping position of the infant, the prevention of neural tube defects by periconceptional folate supplementation, and the improvement of vision and other health outcomes by giving children vitamin A supplements. Yet over the same time period, the discipline was shaken by events that made the limitations of studying risk factors all too apparent. Notably, epidemiologists were caught unprepared by the AIDS pandemic. The identification of sexual and drug use behaviours as risk factors for HIV transmission was a timely and extremely important, but nowhere near sufficient, response to what became a public health catastrophe. Such events have provoked many of us to rethink our designs and methods. This is reflected in a surge of experimentation with other approaches, including mathematical modelling of infectious disease epidemics and other dependent happenings, analysis of historical trends, multilevel studies that take account of contextual variables, life course studies that examine the developmental origins and trajectory of health and disease, and designs, such as Mendelian randomization, that make use of genomics to answer epidemiological questions. 1