Main registers used
Information from Danish national registers can be linked through the unique personal identifier issued to all Danish residents since 1968. Through additional linkage to large Danish biobanks an extra dimension has been added to this favorable opportunity for large scale research projects.
The purpose of the Danish Biobank Registry is to facilitate the utilization of the possibility to link Danish registers and biobanks by providing scientists with estimated numbers of biological specimens available for research projects.
The Danish Civil Registration System
The Danish Civil Registration System (CRS) was introduced April 2, 1968, and has since assigned unique identification numbers to all Danish residents. For each individual the register includes individual information on the unique personal identification number, name, gender, date of birth, place of birth, citizenship, identity of parents and continuously updated information on vital status, place of residence and spouses (CB Pedersen 2011). Historically, the register also includes information on maternal and, if known, paternal identity for all persons born since 1960 (and alive in 1968), and correspondingly, information on all children (alive in 1968) born to women born since 1935 (alive in 1968). CRS contains complete information on immigrations and emigrations from 1969 onwards, permanent residence in a Danish municipality from 1971 onwards, and full address in Denmark from 1977 onwards.
The Danish National Patient Register
The Danish National Patient Register (NPR) was established in 1977. Using the CRS number as key, the register includes information on all hospital contacts, the most important variables being hospital department, date and time for hospital arrival and departure, outpatient contact, treatment, and operation, referral diagnosis, action diagnosis, other diagnoses, and type of operation, examination, and treatment (Lynge et al., 2011). The scope of the register has gradually been expanded over the years, in the beginning being limited to all admissions to somatic departments, then in 1994 expanded to include also outpatient contacts to somatic departments and in 2007 to include information on contacts with psychiatric departments.
The Danish Pathology Register
The Danish Pathology Register (DPR) was established in 1997. Using the patient CRS number as key the DPR contains information on all pathological examinations carried out in Denmark, the most important variables in the present context being ID-number for the examination, investigating pathology department or practicing pathologist, type of investigation, gross description, microscopy description, conclusion and/or diagnoses, and coded diagnoses based on the Danish SNOMED (Bjerregaard & Larsen, 2011). Nationwide since 1997, the register also includes data from various periods of time before 1997 from the participating departments.