Funding for this research was provided by:
Høgskolen i Oslo og Akershus
Received: 27 August 2019
Accepted: 28 February 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: HUNT3 was approved by the Regional Committee for Medical Research Ethic (REK), Mid-Norway. The participation is voluntary, and all participants signed written informed declaration and consent before inclusion in the study. All future research projects must gain approval from the ethical committee, and this study was approved by REK (2012/2264) and the Norwegian Social Science Data Service (NSD) (16/00284–4). The NSD gave their permission to linkage NorPD data from the Norwegian Institute of Public Health (PDB 1582) with data from the HUNT Research Centre. Participants in the HUNT3 had also provided an extended informed consent, which allowed linkage between the databases.
: Not applicable.
: The authors report that they have no conflicts of interest. The authors alone are responsible for the content and writing of the paper.