1. Schroeder Arthritis Institute, Toronto Western Hospital, Spondylitis Program, University Health Network , Toronto, ON, Canada
2. Department of Clinical Epidemiology, College of Medicine, University of the Philippines Manila , Manila, Philippines
3. Division of Neurology, Department of Medicine, St. Michael’s Hospital, University of Toronto , Toronto, ON, Canada
4. Division of Rheumatology, Department of Medicine, University of Jeddah , Jeddah, Saudi Arabia
5. Schroeder Arthritis Institute, Toronto Western Hospital, University Health Network , Toronto, ON, Canada
6. Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network , Toronto, ON, Canada
7. Biostatistics Division, Dalla Lana School of Public Health, University of Toronto , Toronto, ON, Canada
8. Centre for Prognosis Studies in the Rheumatic Diseases, Schroeder Arthritis Institute, University Health Network , Toronto, ON, Canada
9. Temerty Faculty of Medicine, University of Toronto , Toronto, ON, Canada