title: [The research protocol II: study designs in clinical research].
abstract: In clinical research that takes place in health-care areas, most of the studies are performed with human beings as research subjects. The main objectives of these studies are to know the characteristics of one or more groups, the behavior of human diseases, the etiology or causes of diseases, to identify the best diagnostic tools, or to establish the best treatment for a condition or disease in particular. Additionally, some studies are classified as basic bio-medical research; in these investigations, the subjects of study are laboratory animals, tissues, cells, or molecules. In general terms, the objectives of these studies are to understand the physiology, pathogenesis, or biological mechanisms that could explain functions or alterations in one or more systems or body organs. This article will only address clinical research designs.
authors.affiliation: Unidad de Investigación en Epidemiología Clínica, Hospital de Pediatría, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México. guadalumiranda@terra.com.mx.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Villasís-Keever
authors.forename: María Guadalupe
authors.initials: MG
authors.lastname: Miranda-Novales
mesh_terms: D000818:Animals; D035843:Biomedical Research / Q000379:methods*; D003933:Diagnosis; D004194:Disease / Q000209:etiology; D006801:Humans; D012107:Research Design; D013812:Therapeutics
keywords: clinical research; study designs