1. Wolfson Institute of Population Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London , London, UK
2. Institute for Musculoskeletal Health , Sydney, NSW, Australia
3. Sydney School of Public Health, Faculty of Medicine and Health, The University of Sydney , Sydney, NSW, Australia
4. Department of Chiropractic Medicine, Faculty of Medicine, University of Zurich and Balgrist University Hospital , Zurich, Switzerland
5. Epidemiology, Biostatistics and Prevention Institute, University of Zurich , Zurich, Switzerland