Funding
Open access funding provided by University of Bergen. This work was supported by The Norwegian Research Council (BEHANDLING, contract no 269855); and the Western Norway Regional Health Authority («Åpen prosjektstøtte») with Department of Addiction Medicine, Haukeland University Hospital, Bergen, Norway as responsible institution. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors were funded by their respective affiliations.