Funding for this research was provided by:
Norges Forskningsråd (213477)
Sørlandet Hospital, Addiction Unit
Sørlandet Hospital, BarnsBeste
the Norwegian Directorate of Health
Received: 23 August 2020
Accepted: 22 June 2021
First Online: 30 June 2021
: The study was approved by the Regional Committee for Medical Research Ethics (REK), Approval No. 2012/1176 A. Informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.