III. Causality Studies

Abstract

Although the need of solving a clinical problem leads to the establishment of a starting point for approaching it (risk, prognosis or treatment study), in all cases, there is an attempt to attribute causality. Clinical reasoning, analyzed in detail in the book Clinical Epidemiology. The architecture of clinical research offers a simple guideline for undestanding this phenomenon and uses three components: baseline state, maneuver and outcome. In this model, different systematic errors are described (biases), which can occur when features of these basic components are overlooked. Omisions of characteristics at the baseline state produce an inadequate assembly of the population and the susceptibility bias; in the application or assessment of the maneuver, the execution bias; and in the assessment of the outcome, the detection bias and the transference bias. Thus, it is important to emphasize that if this form of reasoning facilitates the comprehension of the causal phenomenon, variables to be selected in studies where causality will be attributed or not to them require additional clinical reasonings assessing their relevance.