Received: 8 May 2019
Accepted: 30 July 2019
First Online: 8 August 2019
Ethics approval and consent to participate
: The Regional Committee for Medical and Health Research Ethics, REC South East, approved the study (2016/389).Written informed consent was obtained from all participants in the Tromsø Study.
: Written obtained consent to publish from all participants in the Tromsø Study.
: The authors declare that they have no competing interests.