Funding for this research was provided by:
Helse Sør-Øst RHF
Nasjonalforeningen for Folkehelsen
Received: 6 September 2019
Accepted: 1 May 2020
First Online: 4 June 2020
Ethics approval and consent to participate
: Both studies were approved by the South-East Regional Committee for Medical and Health Research Ethics in Norway and the HITTS study was additionally approved by the Committee for Medical and Health research in Sweden and Denmark [CitationRef removed]. The studies were conducted in accordance with recommendations in the Helsinki Declaration. All participants provided written informed consent before inclusion in the studies. ExternalRef removed identifiers: NCT01091194 and NCT01796379.
: Not applicable.
: The authors declare that they have no competing interests.