Nordic Health Registry-Based Research: A Review of Health Care Systems and Key Registries

Figures & data

Figure 1 Population statistics for the five Nordic countries, 2018.

Notes: Data from the World Bank (2018).

Figure 2 Key spending in the Nordic health care systems, 2018/2019 or latest available.

Notes: Data from OECD. GDP: gross domestic product. Total hospital beds include curative (or acute) care beds, rehabilitative care beds, long-term care beds and other beds in hospitals. The indicator is presented as a total and for curative care and psychiatric care.

Figure 3 Overview of the operational organization of the Nordic health care systems.

Notes: ^aIncludes physiotherapists, dentists, psychologists, and specialized medical doctors working in private practice as eg. dermatologists, otorhinolaryngologist, fertility treatment specialists, cardiologists and pulmonologists. Visits to dentist never require referral from general practitioners (GPs). Other specialists may be accessed with or without referral from GPs; however, patient co-payment is often larger without a referral. Some private clinics are reimbursed completely or partly by public funding and some rely solely on patient self-payment or private insurance. Specialized medical doctors in private practice can refer patients to hospitals if needed. In Sweden, it is also possible to self-refer to hospital specialists. Patients need to fill out an online form, and then a hospital specialist will decide whether to see the patient without a GP referral.

Figure 4 Combining Nordic registries by personal identity number.

Notes: Other registries and databases refer to registries containing socioeconomic data, the numerous disease or procedure registries, clinical quality databases/registries, surveys, researcher-initiated cohorts and biobanks.

Figure 5 The time coverage of selected Nordic population-based registries.

Notes: Only the time for complete nationwide coverage is displayed. The Finnish Hospital Discharge Register has had nationwide coverage since 1967 but was limited by incomplete registration of the personal identity number in 1967-1968 and diagnoses in 1967-1970. The Icelandic Birth Registry was complete from 1972 but electronically since 1981.

Table 1 Key Variables in the Nordic Total Population Registries

Variables
Personal identity number
Sex
Date of birth
Country of birth
Name
Address, including date of address changes
Immigration and date
Emigration and date
Civil status, including changes in and personal identity number of spouse or registered partner
Kinship, including personal identity number of parents, siblings, and children
Date of death

Table 2 Selected Key Variables in the Nordic Birth Registries

Information Type	Variables
Basic information	The personal identity number of the infant
	The personal identity number of the mother
	The personal identity number of the father^a
Delivery information	Date of birth
	Place of birth
	Presentation at birth (eg, cephalic, breech, or shoulder presentation)
	Method of delivery
	Delivery complications
	Procedures around delivery
Maternal characteristics	Age at birth
	Height, weight, body mass index^b
	Smoking status^c
	Parity
	Diagnoses^d and complications during pregnancy or delivery
	Number of previous pregnancies and deliveries
Infant characteristics	Single or multiple birth
	Sex
	Gestational age at birth
	Birth weight
	Length
	Head circumference
	Live or stillborn^e
	Health status of the child (Apgar score, infant diagnoses, and treatment)
	Congenital malformations at birth^f

Notes: ^aNot in Sweden and Finland but can be obtained through linkage to the total population registries. ^bThe coverage period of these variables varies considerably across the countries. ^cSweden also record use of snuff. ^dNot recorded in the Danish Medical Birth Registry, but some diagnoses may be obtained through linkage to the Patient Registry. ^eGestational age at which stillbirth is defined varies by country and calendar year. ^fMore detailed information may be obtained in the registries of congenital anomalies or patient registries, depending on country. The birth registries of Norway and Sweden also contain information on fertility treatment procedures and indications.

Table 3 Selected Key Variables in the Nordic Patient Registries

Information Type	Variables
The patient	Personal identity number
	Area of residence
Hospital and department	Hospital code
	Department code/specialty
Admission	Admission date
	Discharge date
	Admission type (acute, non-acute, etc.)
	Patient contact type (eg, inpatient, outpatient)
	ICD diagnoses (primary and secondary/additional codes)
	Surgical and medical procedure codes

Abbreviation: ICD, the International Statistical Classification of Diseases and Related Health Problems for coding diagnoses.

Table 4 Timeline for Use of the International Statistical Classification of Diseases and Related Health Problems (ICD) Coding Systems in the Patient Registries by Country

	ICD-7	ICD-8	ICD-9	ICD-10
Denmark	NA	1977–1993	NA	1994-
Sweden	1964–1967^a	1968^a-1986	1987–1996	1997^b-
Norway	NA	NA	1997–1998	1999-
Finland	NA	1969–1986	1987–1995	1996-
Iceland	NA	NA	NA	1999-

Notes: ^aOfficially, the change to ICD-8 occurred in 1968, but in practice ICD-7 was used during 1968, and only in 1969 was ICD-8 used. ^bThe Skåne region introduced ICD-10 in 1998. Source: Health Classifications in the Nordic Countries (2006). Björn Smedby and Gunnar Schiøler. Responsible organization: Nordic Council of Ministers, NOMESCO-NOSOSCO. (http://norden.diva-portal.org/smash/get/diva2:970544/FULLTEXT01.pdf).

Abbreviation: NA, not applicable.

Table 5 Selected Key Variables in the Nordic Cancer Registries

Information Type	Variables
The patient	Personal identity number
	Date of birth
	Sex
	Place of residence (unit)
	Vital status
	Date of death
Tumor characteristics	Date of diagnosis
	Topography (primary site)
	Morphology/histology
	Tumor stage or grade^a
	Method of confirmation
	Behavior (malignant, premalignant, and borderline behavior)

Note: ^aClassification system depends on country, calendar year, and cancer type.

Table 6 Selected Key Variables in the Nordic Prescription Registries

Information Type	Variables
The patient	Personal identity number (or pseudonymized number)
	Sex
	Date of birth
The prescriber	Prescriber type (eg, GP, hospital physician, or private physician)
The pharmacy	Identifier
	Location of the pharmacy^a
The drug	Date of dispensing
	Nordic article number (unique identifier)
	Anatomical Therapeutic Chemical classification (ATC) code
	Number of packages dispensed
	Number of tablets in one package
	Tablet strengths
	The defined daily dose (DDD)
	Formulation of the drug
	Drug reimbursement

Note: ^aLocation not recorded in the Finnish prescription registry but can be linked.

Table 7 Selected Key Variables in the Nordic Causes of Death Registries

Information Type	Variables
The person	Personal identity number
	Place of residence
The death	Date of death (or date of discovery if found dead)
	Manner of death (natural, accident, violence, suicide, uncertain)
	Underlying cause of death
	The immediate or direct cause of death^a
	The contributing causes of death
	Place of death (private residence, nursing home, hospital)
	Autopsy performed (yes/no)
	Type of autopsy (clinical, medico-legal)
Physician issuing the death certificate	Hospital physician, GP, health officer, etc

Notes: ^aThe Swedish Causes of Death Registry does not record immediate/direct cause of death directly. Nevertheless, this information can mostly be obtained by the position of the cause of death on the death certificate (the first line on the death certificate corresponds to the immediate/direct cause of death).

Table 8 Country-Specific Overview of Permission Needed for Registry-Based Research and Where to Apply for Data

	Required Permissions	Where to Apply for Data
Denmark	Approval from the Danish Data Protection Agency; from a practical perspective this is done by reporting the study to local authorities with data responsibility (universities or regions) No ethical permission is needed	The Danish Health and Medicines Authority (www.sundhedsdatastyrelsen.dk) Statistics Denmark (www.dst.dk)
Sweden	Approval from the relevant governmental registry holder (Statistics Sweden and the National Board of Health and Welfare) Ethical permission is required from the Ethical Review Authority.	The National Board of Health and Welfare (www.socialstyrelsen.se) Statistics Sweden (www.scb.se)
Norway	Ethical permission is required from the regional ethical committee	Helsedata (www.helsedata.no) Statistics Norway (www.ssb.no)
Finland	Approval from the Health and Social Data Permit Authority (Findata) and/or Statistics Finland No ethical permission is needed	Findata (www.findata.fi) Statistics Finland (www.stat.fi)
Iceland	Approval from the National Bioethics Committee (including a review from the National Data Protection Agency) Approval from the relevant governmental registry holder	The Directorate of Health (www.landlaeknir.is) Statistics Iceland (www.statice.is)