Funding for this research was provided by:
The Norwegian Research Fund for General Practice
Received: 10 May 2019
Accepted: 9 August 2019
First Online: 14 August 2019
Change Date: 16 September 2020
Change Type: Correction
Change Details: An amendment to this paper has been published and can be accessed via the original article.
Ethics approval and consent to participate
: Ethical approval was obtained from the Regional Ethical Committee for Medical and Health Research Ethics, Region West (30.01.2014) (reference number 2013/2344/REK vest) and Norwegian Data Protection Authority (15.09.2014) (reference number 14/0322–9/CGN). The Regional Ethical Committee for Medical and Health Research Ethics, Region West gave permission to use the data without asking the patients for consent. Norwegian Data Protection Authority approved the use of the data for research purposes in this project. The register owners, Statistics Norway and the Norwegian Directorate of Health, approved linkage of registries. The data were pseudo anonymized by third party (Statistics Norway), and analyzed at group level to minimize the risk for individuals to be identified.
: Not applicable.
: The authors declare that they have no competing interests.