1. Norwegian Institute of Public Health , Oslo 0213 , Norway
2. Innlandet Hospital Trust National Advisory Unit on Concurrent Substance Abuse and Mental Health Disorders, , Brumunddal 2381 , Norway
3. Institute of Clinical Medicine, UiT–The Arctic University of Norway , Tromsø 9037 , Norway
4. Inland Norway University of Applied Sciences , Elverum 2406 , Norway
5. Lillogata 5 P , Oslo 0484 , Norway
6. Institute of Clinical Medicine, University of Oslo , Oslo 0316 , Norway