[1] Tecnol Monterrey, Esculea Med, Monterrey, Mexico
[2] Qmetr Technol, Rochester, NY USA
[3] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA USA
[4] Univ Pittsburgh, Div Rheumatol & Clin Immunol, Pittsburgh, PA USA
[5] Royal N Shore Hosp, Sydney, NSW, Australia
[6] Univ Sydney, Northern Clinial Sch, Sydney, NSW 2006, Australia
[7] Univ Arizona, Div Rheumatol, Tucson, AZ USA
[8] Univ Arizona, Arthrit Ctr, Tucson, AZ USA