1 HUNT Research Centre, Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.
3 Department of Community Medicine, Center for Sami Health Research, Arctic University of Norway, Tromso, Norway.
4 HUNT Center for Molecular and Clinical Epidemiology, Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology), Trondheim, Norway.
5 Department of Research, St Olav's Hospital, Trondheim, Norway.