[1] Univ Oslo, Fac Med, Oslo, Norway
[2] Diakonhjemmet Hosp, Div Rheumatol & Res, Oslo, Norway
[3] Univ Hosp Northern Norway, Dept Rheumatol, Tromso, Norway
[4] Helse Forde, Sect Rheumatol, Dept Neurol Rheumatol & Phys Med, Forde, Norway
[5] Lillehammer Hosp Rheumat Dis, Dept Rheumatol, Oslo, Norway
[6] Oslo Univ Hosp, Dept Rheumatol, Oslo, Norway