Funding for this research was provided by:
Helse Vest (912043, 911775)
Received: 6 October 2018
Accepted: 6 May 2019
First Online: 17 May 2019
Ethics approval and consent to participate
: The study was performed according to the Declaration of Helsinki and approved by the Regional Ethics Committee West (2010/1455). All participants gave written consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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