[Study designs adopted in epidemiology of chronic diseases]

Clinical research is gaining interest among healthcare professionals. This review provides an in-depth analysis of key study designs used in epidemiology, which can help researchers use the right methodology to design and conduct a research project. Case-control studies evaluate the association between an exposure to a specific risk factor and a study endpoint. Cross-sectional studies are indicated to assess the prevalence of a given risk factor. Cohort studies consist of longitudinal studies, in which a population is followed over time. These studies allow to evaluate the association between a risk factor and one or more study endpoints which are absent at the time of the population enrollment. Experimental studies are designed to test the efficacy and safety of an intervention. Generally, they include two groups of individuals who are assigned to either an experimental treatment or a standard treatment, respectively. Meta-analyses are studies that summarize the evidence already published concerning a specific research question and constitute an important source for evidence-based medicine and for the production and updating of guidelines.