1. Norwegian Centre for Addiction Research (SERAF) Institute of Clinical Medicine University of Oslo Oslo Norway
2. School of Pharmacy Faculty of Health Sciences University of Eastern Finland Kuopio Finland
3. Department of Mental Disorders Division of Mental and Physical Health the Norwegian Institute of Public Health Oslo Norway
4. Department of Circulation and Medical Imaging Faculty of Medicine and Health Sciences Norwegian University of Science and Technology Trondheim Norway
5. Norwegian Advisory Unit on Complex Symptom Disorders St. Olav University Hospital Trondheim Norway
6. Department of Palliative Medicine Akershus University Hospital Lørenskog Norway
7. Centre for Pharmacoepidemiology and Drug Safety Division of Pharmacy and Optometry School of Health Sciences Faculty of Biology, Medicine and Health University of ManchesterManchester Academic Health Science Centre Manchester UK