Overview of cohort studies

BACKGROUND: A cohort study is an epidemiological design in which the frequency of a disease is compared between populations in order to measure the causality of different risk factors; however, due to their great variety of terms, they hinder the correct interpretation of the results. OBJECTIVE: to analyze the main characteristics of the cohort study to facilitate the perform and interpretation of its results. DESCRIPTION: this design is characterized by being a observational and longitudinal study; whose observations identify the causal relationship between the risk factors and the outcomes of interest. According to their variables, the cohorts can be classified as prospective, retrospective or ambispective. In this design, participants who do not present the event of interest at the beginning of the study are included; and after a time then they are compared to identify how many of them developed it and which were the risk factors that they had for developing the disease. Therefore, this type of study allows to know incidence of the event and determine the causal relationship of the different factors expressed by relative risk. CONCLUSIONS: the cohort study is considered the best design to analyze the causality; However, it is costly and difficult to perform, because it uses different techniques to reduce the sources of bias to ensure the reliability of its results.