[1] Univ Toronto, Toronto Western Hosp, Ctr Prognosis Studies Rheumat Dis, Hlth Network,Psoriat Arthrit Program, Toronto, ON M5T 2S8, Canada
[2] Univ Toronto, Rheumat Dis Unit, Toronto, ON M5T 2S8, Canada
[3] Univ Washington, Sch Med, Seattle Rheumatol Associates, Seattle, WA 98195 USA
[4] Univ Washington, Sch Med, Swedish Rheumatol Res Div, Seattle, WA 98195 USA
[5] Abbott Labs, Global Pharmaceut Res & Dev, Global Hlth Econ & Outcomes Res, Abbott Pk, IL 60064 USA
[6] Abbott Labs, Clin Stat, Abbott Pk, IL 60064 USA
[7] Abbott Labs, Abbott Immunol, Abbott Pk, IL 60064 USA
[8] Abbott Labs, Immunosci, Rheumatol, Abbott Pk, IL 60064 USA