[1] Univ Toronto, Toronto, ON, Canada
[2] Univ Waterloo, Waterloo, ON N2L 3G1, Canada
[3] Univ Alberta, Edmonton, AB, Canada
[4] Univ Hosp Maastricht, Maastricht, Netherlands
[5] Rheumazentrum, Herne, Germany
[6] Univ Calif San Francisco, San Francisco, CA 94143 USA
[7] Univ Washington, Seattle, WA 98195 USA
[8] Hosp Gen Mexico City, Mexico City, DF, Mexico
[9] Univ Leeds, Leeds, W Yorkshire, England
[10] Univ Calif San Diego, San Diego, CA 92103 USA
[11] Case Western Reserve Univ, Cleveland, OH 44106 USA
[12] Arcispedale Santa Maria Nuova, UO Reumatol, Viale Risorgimento, Italy
[13] Mem Univ Newfoundland, St John, NF, Canada
[14] Univ Texas, Houston, TX USA
[15] Royal Natl Hosp Rheumat Dis, Bath BA1 1RL, Avon, England
[16] Wellington Sch Med, Wellington, New Zealand
[17] St Vincents Univ Hosp, Dublin, Ireland