Funding for this research was provided by:
Norsk Sykepleierforbund (15/0015)
Article History
Received: 6 August 2018
Accepted: 19 July 2019
First Online: 14 August 2019
Ethics approval and consent to participate
: The study followed the guidelines of the Helsinki Declaration and was approved by the Regional Committee for Medical and Health Research Ethics (ID No:2014/1523). A written informed consent was obtained by patients/ controls and signed in advance of inclusion. All data were stored with a numeric identifier in a separate, secured research database detached from the identifier code list, approved by the local privacy protection board.
: Not applicable.
: The authors declare that they have no competing interests.