What can epidemiological methods mean to surgical research?

Traditionally, the aim of epidemiological research has been to determine and explain the incidence of a disease and thereby ultimately to reveal its causative mechanisms. Clinical research, or clinical epidemiology, on the other hand, has been devoted primarily to the evaluation of diagnostic and therapeutic techniques and to investigation of the course of a disease after its diagnosis. The aim of this brief discussion is to illustrate how these two areas of research--epidemiological and clinical--have the same methodological roots and use similar biostatistical tools. Whether they are carried out as experimental or as observational studies, the fundamental problem in the scientific method is to achieve validity by attenuating or controlling the effects of extraneous factors that influence the outcome under study. In modern epidemiology powerful methods of reaching this goal have been developed and thus a sound basis has been provided for drawing reliable conclusions concerning causal relations between "exposures" and outcomes. If surgical researchers become aware that epidemiological and clinical researchers obtain their scientific tools from the same conceptual domain and become familiar with the methods used in traditional epidemiology, this will probably result in fruitful scientific expansion in clinical surgery.