Funding for this research was provided by:
Norges Forskningsråd (214298)
Received: 9 August 2018
Accepted: 13 March 2019
First Online: 4 April 2019
Ethics approval and consent to participate
: The Regional Committee for Medical and Health Research Ethics granted approval for the research project (approval number 2012/852), and all registry owners consented to their data being utilized. As the study utilised existing registry data, no written or verbal consent to participate was required.
: Not applicable
: The authors declare that they have no competing interests.
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