Data sources

In the Danish Central Population Register a unique and permanent civil registration number for each individual resident in Denmark is held. Upon contact with any part of the public system, e.g., healthcare services, the civil registration number is registered in the appropriate administrative register along with an action code. Linkage of information across registries is feasible on the individual level through the civil registration number.

Registrations from 5 different national administrative registries were retrieved in this study: the Central Population Registry, Danish National Patient Registry, National Prescription Registry, Nursing Home Registry, and Household Income Registry.