title: Epidemiology. When an entire country is a cohort.
authors.forename: L
authors.initials: L
authors.lastname: Frank
mesh_terms: D015331:Cohort Studies; D003219:Confidentiality; D016208:Databases, Factual; D003718:Denmark / Q000453:epidemiology; D036281:Genetic Research; D006801:Humans; D016347:Medical Records Systems, Computerized; D012042:Registries; D018433:Twin Studies as Topic