1. Department of Public Health and Nutrition, Faculty of Health and Sport Sciences, University in Agder, P.O. Box 422, 4604 Kristiansand, Norway
2. Department of Health and Nursing Science, Faculty of Health and Sport Sciences, University in Agder, 4604 Kristiansand, Norway
3. Department of Nursing and Health Promotion, Faculty of Health Sciences, Akershus University College of Applied Sciences, 0167 Oslo, Norway
4. Department of Clinical Research, Sorlandet Hospital, 4615 Kristiansand, Norway