1. Institute of Medical and Biological Engineering, University of Leeds, Leeds LS2 9JT, UK
2. Warwick Clinical Trials Unit, University of Warwick, Coventry CV4 7AL, UK
3. Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds LS2 9JT, UK
4. Leeds Institute of Health Informatics, University of Leeds, Leeds LS2 9JT, UK