1. Department of Family Medicine and Population Health, Division of Epidemiology, Virginia Commonwealth University, Richmond, Virginia.
2. Department of Physical Medicine and Rehabilitation, Oslo University Hospital Ulleval, Oslo, Norway.
3. Institute of Clinical Medicine, Research Centre for Habilitation and Rehabilitation Models and Services (CHARM)
4. Institute of Health and Society, Research Centre for Habilitation and Rehabilitation Models and Services (CHARM)
5. Department of Health Management and Health Economics, Faculty of Medicine, University of Oslo, Oslo,
6. Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, Massachusetts.
7. Carolinas Rehabilitation, Carolinas Healthcare System, Charlotte, North Carolina.
8. University of Deusto. IKERBASQUE, Basque Foundation for Science. Bilbao, Spain.