Table 1.

Data sources and information obtained.

Data source	Register holder	Information obtained
National prescription register	The Social Insurance Institution of Finland	Dispensed opioids reimbursed by the state
Register on long-term sick leave	The Social Insurance Institution of Finland	Decision on long-term sick leaves
Reimbursement register	The Social Insurance Institution of Finland	Decisions for reimbursement of private sector health care use
Care register for secondary and primary health care	National Institute for Health and Welfare	Diagnoses (ICD-10 codes) and interventions
Cause of death register	Statistics Finland	Deaths and causes of deaths
Register of completed education and degrees	Statistics Finland	Education level
Population register	Population Register Center	Date of birth and place of domicile