X. From Clinical Judgment to Cohort Design

Abstract

After the clinical trial, the second research design with the best quality of information is the cohort. Although the possibility of randomization of the maneuver is not available, there is the opportunity of having the subjects followed over time. Any research that tries to explain the causality fenomenon is at risk of incurring biases; however, the cohort studies distinctive features try to avoid them. Its main characteristics are: 1 being observational, situation where the investigator only measures the presence of the maneuver, which is a characteristic that divides the subjects into exposed and non-exposed; 2 being longitudinal, which offers the opportunity to follow the subject over time, documenting the time-sequence of appearance of the causality phenomenon components; 3 measurements have directionality, which generates the existence of prolective, retrolective and retro-prolective cohorts (the first are the ones with the highest quality, since they perform a real-time measurement of the variables of interest; 4 being comparative.