Table 7.

Use of the Danish National Patient Registry according to study design

Cohort studies	Identifying study cohorts from hospitalized patients, the general population (assessed from registries or in combination with primary data collection), and family cohorts (constructed through linkage to the Danish Civil Registration System)
	Identifying study exposures related to diseases, treatments, examinations, and seasonality
	Identifying disease occurrence in the general population (eg, associated with lifestyle factors identified from health surveys) or family cohorts
	Identifying disease outcome (recurrence or complications) in patients identified from the DNPR itself, clinical registries, or randomized trials
	Identifying health care utilization rates through counting frequency of inpatient/outpatient and planned/unplanned contacts
	Identifying temporal trends in disease incidence and use of treatments and diagnostic procedures
Case–control studies	Identifying cases (and exposure from the DNPR, other registries, health surveys, or primary data collection). Risk-set sampling is possible through linkage to the Danish Civil Registration System
Cross-sectional studies	Identifying patient’s medical history at study entry according to diagnoses (index disease and comorbidities), treatments (in-hospital medical treatment, surgical procedures, anesthesia, and intensive care), and diagnostic procedures
Ecological studies	Identifying variations in health care and outcomes at the population level

Abbreviation: DNPR, Danish National Patient Registry.