[1] Univ Toronto, Toronto Western Hosp, Toronto Psoriat Arthrit Res Program, Toronto, ON, Canada
[2] Univ Toronto, Toronto Western Hosp, Rheumatol, Toronto, ON, Canada
[3] Univ Toronto, Toronto Western Hosp, Spondylitis Clin, Toronto, ON, Canada
[4] Toronto Western Hosp, Rheumatol, Toronto, ON, Canada
[5] Univ Waterloo, Stat & Actuarial Sci, Waterloo, ON, Canada