Funding for this research was provided by:
Helse Nord RHF (N.a.)
AbbVie AS Norway (N.a.)
UiT The Arctic University of Norway (N.a.)
Article History
Received: 31 October 2018
Accepted: 19 February 2019
First Online: 26 February 2019
Ethics approval and consent to participate
: The Tromsø study was conducted by UiT The Arctic University of Norway. The Regional Committee for Medical and Health Research Ethics (REK) approved the study (ref: 2014/1406 and 2017/253), and all participants gave their written consent.
: Not applicable.
: The authors declare that they have no competing interests.
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