Funding for this research was provided by:
Vestfold Hospital Trust, Norway
Institute of Clinical Medicine, University of Oslo, Norway
MRK Foundation, Norway
Josef and Haldis Andresens Legat, Norway
Received: 7 September 2020
Accepted: 13 January 2021
First Online: 17 February 2021
Ethics approval and consent to participate
: Regional Committees for Medical and Health Research Ethics in Norway approved the study protocol and the information given to the patients (REC Central, 2011/1424). Written informed consent to participate in this trial was obtained from each participant, aged 16–18 years at inclusion. According to Norwegian legislation, ethical consent for participation in research may be given from age 16.
: Please see the previous paragraph.
: The authors declare that they have no competing interests.