[1] Skanes Univ Sjukhus, Malmo, Sweden
[2] Linkoping Univ, Linkoping, Sweden
[3] Univ Copenhagen, Rigshosp, Ctr Rheumatol & Spine Dis, Copenhagen Ctr Arthrit Res, Copenhagen, Denmark
[4] Univ Copenhagen, Herlev & Gentofte Hosp, Copenhagen, Denmark
[5] Ryhov Hosp, Jonkoping, Sweden
[6] Haukeland Hosp, Bergen, Norway
[7] UiT Arctic Univ Norway, Tromso, Norway
[8] Univ Hosp North Norway, Tromso, Norway
[9] Aarhus Univ Hosp, Aarhus, Denmark