[1] Univ Alberta, Edmonton, AB, Canada
[2] Leiden Univ, Med Ctr, Dept Rheumatol, Meerssen, Netherlands
[3] Rocky Mt Reg VAMC, Aurora, CO USA
[4] Univ Amsterdam, Med Ctr, Meerssen, Netherlands
[5] Univ Calif San Francisco, Dept Med Rheumatol, San Francisco, CA 94143 USA
[6] Univ Coll London Hosp NHS Fdn Trust, Dept Rheumatol, London, England
[7] London North West Univ Healthcare NHS Trust, Northwick Pk Hosp, Dept Rheumatol, London, England
[8] UCL, Ctr Rheumatol, London, England
[9] UCL, Dept Neuromuscular Dis, London, England
[10] Leiden Univ, Med Ctr, Portela Loures, Portugal
[11] LUMC, Leiden, Zuid Holland, Netherlands
[12] Charite Univ Med Berlin, Berlin, Germany
[13] Oregon Hlth & Sci Univ, Div Arthrit & Rheumat Dis, Portland, OR 97201 USA
[14] Univ Bielefeld, Klinikum Bielefeld, Bielefeld, Germany