Article History
Received: 9 January 2019
Accepted: 12 March 2019
First Online: 20 March 2019
Ethics approval and consent to participate
: We made use of a secondary anonymised dataset collected by Statistics Norway. Because the dataset was anonymised, specific ethical approval was not required for this study and was waved by the Norwegian Centre for Research data. A confidentiality agreement with the Norwegian Centre for Research Data was signed in order to use the data. We conducted the analyses in accordance with the Norwegian Centre for Research Data’s data protection regulations.Consent to participate was not needed due to the retrospective nature of the study.
: Not applicable as this was an anonymised secondary data source.
: The authors declare that they have no competing interests.
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