1. The Norwegian National Centre for Ageing and Health, Vestfold Hospital Trust, Tønsberg, Norway
2. The Norwegian National Centre for Ageing and Health, Vestfold Hospital Trust, Tønsberg, Norway; and Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
3. Faculty of Health and Social Sciences, University of South-Eastern Norway USN, Porsgrunn, Norway