1. Department of Health Services Research, Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
2. Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands
3. Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
4. Institute of Clinical Medicine, Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
5. WHO Collaborating Centre for Public Health Aspects of Musculo-Skeletal Health and Ageing, Division of Public Health, Epidemiology and Health Economics, University of Liège, Liège, Belgium