Guidelines of how to report an observational epidemiological study in health: Essential elements

Abstract

This paper provides some brief guidelines about what aspects are relevant when planning an observational epidemiological study and, consequently, what basic information should be taken into account when reporting this type of study. Thus, a distinction is made between prevalent cases and incident cases, as well as a differentiation between descriptive studies and relational studies. The former are basically used to determine the health status of the population while the latter are focused on the study of the etiology of the disorder under study. In the relational studies, we differentiate between cross-sectional, cohort and case-control studies, and for each of them the basic elements to be taken into account are specified, such as the definition of the observation period and, consequently, the time at risk, the determination of the disorder status, the exposure status and other factors to be taken into account. In this last point, special reference is made to the importance of the reliability and validity of the measurement instruments used to determine this status, and, in particular, to some epidemiological indices such as sensitivity and specificity as well as predictive values.