Table 1

Data sources, Danish national registries

The Danish Civil Registration systemEstablished in year 1968. All persons alive and living in Denmark are registered for administrative use. Includes complete information on civil registration number, name, gender, date of birth and continuously updated information on vital status, marital status and place of residence (including immigration and emigration).41
The Danish National Patient RegistryDiagnoses listed according to the International Classification of Diseases (ICD) codes from all hospital admissions (from 1977) and outpatient activities (from 1995) in the form of the 8th revision of the ICD (ICD-8) until 1994 and the 10th revision (ICD-10) thereafter. Contains information on surgeries and other procedures performed at hospitals. The register is practically complete.42
The Danish Rheumatology Database, DANBIOInitiated in year 2000. Danish national clinical quality registry of rheumatologic patients treated with biologics. In 2006, it became mandatory to register all newly diagnosed RA patients regardless of treatment. >30 000 patients with RA have been registered (unpublished data).
Contains information on for example, ICD-10 diagnosis code of inflammatory rheumatic disease, date of diagnosis, symptom duration, auto-antibody status of rheumatoid factor (RF) and anticitrullinated peptide antibodies (ACPA), current and previous treatment with biologic and synthetic disease-modifying antirheumatic drugs (DMARDs), treatment with glucocorticoids (injection, oral), X-ray results (hands and feet) and prospectively collected disease activity measures including C reactive protein (CRP) and patient-reported outcomes.
Smoking, alcohol consumption and body mass index (BMI) is also registered.43
The Danish National Staphylococcus aureus Bacteremia DatabaseThe nationwide registration of S. aureus bacteremias in Denmark since 1957 carried out by the Staphylococcal Laboratory at the Statens Serum Institut (SSI) for surveillance purposes. Linked to civil registration numbers since 1992. The regional microbiology departments send isolates on a voluntary basis. Has a high degree of completeness and >90% of strains isolated from Danish blood cultures are referred to SSI for typing (detection S. aureus protein A (SPA) type) and antibiotic susceptibility testing.44
The Register of Medicinal Product StatisticsInformation on all prescriptions dispensed from pharmacies has been recorded from 1995 including the anatomical therapeutic chemical class (ATC class), strength, package size, number and date of dispensed prescription.45
The Population’s
Education Registry (PER)
Information on highest attained education. In 2008 PER included 96.4% of the Danish population between 15 and 69 years of age.46
The Income Statistics RegisterInitiated in 1970. Contains information on the income and its composition (eg, salary, taxes and public transfer payments) on an individual level as registered by the Tax Administration’s registry.47
  • All national registries can be linked on an individual basis using the civil registration number administered at birth or immigration.41