The Danish prescription registries.

The extensive computerisation of Danish pharmacies has permitted the establishment of two large prescription registries: The Odense University Pharmacoepidemiological Database (OPED) and the Pharmacoepidemiological Prescription Database of North Jutland (PDNJ). The Danish prescription registries content, coverage, completeness and the quality of the data are discussed in this article. Furthermore, conditions for access to the data are presented. The two prescription registries cover a background population of approximately one million or 18% of the Danish population. The populations covered by the registries are stable and representative of the Danish population in general. The registries cover all reimbursed medicine at the level of the individual user. Registration of a unique and permanent personal identifier enables the compilation of longitudinal drug histories and allows the linking of prescription data to other population-based Danish registries. The degree of completeness of the Danish prescription registries is excellent for reimbursed prescription drugs. A small number of comparison studies also indicate high validity of the register information. The Danish prescription registries represent a useful new data source for pharmacoepidemiological studies.