Database on Danish population-based registers for public health and welfare research.

Population-based studies with information from registers can take place in Denmark due to linkage between registers at the individual level by means of a unique personal identification number (CPR-number), which all persons with residence in Denmark have. Registers with information on health can be linked to other population registers containing information on, for example, transfer payments, education, housing, income, and socioeconomic position. This article introduces a database and search engine, which is available for public health and welfare researchers as an aid to seek information on the content of important Danish registers.