Funding for this research was provided by:
Helse Sør-Øst RHF
Received: 2 March 2020
Accepted: 3 February 2021
First Online: 12 February 2021
Ethics approval and consent to participate
: The project was approved by the Regional Committee for Medical Research Ethics, South-East Norway and all participants (both parents and adolescents) provided written informed consent.
: Not applicable.
: The authors have declared that they have no competing or potential conflicts of interest.