[1] Charite Univ Med Berlin, Berlin, Germany
[2] UCSF, SFVA, San Francisco, CA USA
[3] Univ Calif San Francisco, Div Rheumatol, Gen Dept Med, San Francisco, CA USA
[4] Univ Calif San Francisco, San Rafael, CA USA
[5] Univ Calif San Francisco, San Francisco, CA 94143 USA
[6] Bispebjerg & Frederiksberg Hosp, Parker Inst, Copenhagen, Denmark
[7] Parker Inst, Musculoskeletal Stat Unit, Copenhagen, Denmark
[8] Bispebjerg & Frederiksberg Hosp, Parker Inst, Frederiksberg, Denmark
[9] Charite Univ Med Berlin, Berlin, Germany
[10] Charite Univ Med Berlin, Dept Rheumatol, Berlin, Germany
[11] Charite, Dept Rheumatol, Berlin, Germany