1. Environmental and Occupational Medicine, Population Health Section, Division of Applied Health Sciences, School of Medicine and Dentistry, University of Aberdeen, Foresterhill Road, Aberdeen AB25 2ZP, UK
2. Institute of Occupational Medicine, Research Avenue North, Edinburgh, EH14 4AP, UK
3. Directorate of Sport, Exercise and Physiotherapy, School of Health, Sport and Rehabilitation Sciences, University of Salford, Allerton Building, Frederick Road campus, Salford M6 6PU, UK
4. Department of Rheumatology, Brighton and Sussex Medical School, University of Sussex campus, Falmer, Brighton, BN1 9PX, UK