General concepts in biostatistics and clinical epidemiology: observational studies with cohort design

Abstract

Cohort studies evaluate the relationship between an exposure and the occurrence or lack thereof an outcome of interest, initiating from the exposure. This methodological design has been widely used in some areas of medicine, such as the study of cardiovascular risk factors or the effects of ionizing radiation in humans. It exhibits attractive properties due to its adaptability to various contexts, especially in the study of low occurrence exposures. This is the fourth of a methodological series on general concepts in biostatistics and clinical epidemiology developed by the Chair of Scientific Research Methodology at the School of Medicine, University of Valparaíso, Chile. It covers general theoretical concepts about cohort studies, considering historical aspects, elements related to the construction of a study using this design, variations and derived designs, as well as potential biases that the researcher might face.

Keywords

• observational study
• cohort studies
• relative risk
• incidence
• bias
• epidemiology
• biostatistics