[1] Toronto Western Res Inst, Univ Hlth Network, Div Hlth Care & Outcomes Res, Toronto, ON, Canada
[2] Univ Montreal, Sch Rehabil, Maisonneuve Rosemont Res Inst, Montreal, PQ, Canada
[3] Univ Kansas, Shawnee, KS USA
[4] Univ Alabama Birmingham, Clin Immunol & Rheumatol, Birmingham, AL USA
[5] UCDMC, Int Med, Sacramento, CA USA
[6] UIowa, Iowa City, IA USA
[7] UCSF, Epidemiol & Biostat, San Francisco, CA USA
[8] Boston Univ, Sch Med, Clin Epidemiol Res Unit, Boston, MA 02118 USA
[9] BUSM, Clin Epidemiol, Boston, MA USA