A longitudinal cohort of living individuals who are alike but who differ in terms certain well-defined characteristics followed over time, typically years, to gather information on changes as they occur. It is the gold standard design in epidemiology, for example, in the study of the etiology of disorders and diseases involving the measurement of risk factors (e.g., preterm birth) or exposures (e.g., environment tobacco smoke) before the occurrence of an outcome (e.g., cerebral palsy). The main disadvantage of a prospective cohort study is its expense (e.g., in comparison with a case-control study, especially in terms of the employment of personnel to carry out a study based on this design. Thus, using it requires a careful evaluation in terms of a cost-benefit analysis beforehand. In general, it is considered to be superior to a retrospective cohort study which is less expensive and better able to address rare diseases, but that is subject to problems such as selection bias.
See Cohort, Cerebral palsy, Cross-sectional design, Environmental tobacco smoke (ETS), Etiology, Follow-up studies, Longitudinal design, Panel studies, Preterm birth, Risk factors