[1] Univ Cologne, Dept Dermatol & Venerol, D-50924 Cologne, Germany
[2] Univ Aachen, Dept Rheumatol, D-5100 Aachen, Germany
[3] Univ Cologne, Inst Biostat Informat & Epidemiol, D-50924 Cologne, Germany
[4] Univ Med Ctr Freiburg, Clin Res Unit Rheumatol, Freiburg, Germany
[5] Dresden Univ Hosp, Dept Dermatol, Dresden, Germany
[6] Kerckhoff Clin, Dept Rheumatol & Clin Immunol, Bad Nauheim, Germany
[7] Charite, Berlin, Germany
[8] Hosp Cologne Merheim, Med Clin 1, Cologne, Germany
[9] Univ Munster, Dept Dermatol, D-4400 Munster, Germany
[10] Univ Hosp Charite, Dept Dermatol Venerol & Allergol, Berlin, Germany
[11] Univ Cologne, Dept Rheumatol, D-50924 Cologne, Germany
[12] Johannes Gutenberg Univ Mainz, Dept Dermatol, Mainz, Germany
[13] Univ Munich, Dept Dermatol & Allergol, Munich, Germany
[14] Univ Ulm, Dept Dermatol & Allergol, Ulm, Germany
[15] Univ Regensburg, Dept Dermatol, Regensburg, Germany
[16] Univ Regensburg, Dept Internal Med, Regensburg, Germany
[17] Private Univ Witten Herdecke, HELIOS Klinikum Wuppertal, Dept Dermatol Allergol & Environm Med, Wuppertal, Germany
[18] Hosp Eilbek, Hamburg, Germany
[19] Univ Giessen, Dept Internal Med, D-6300 Giessen, Germany
[20] Clin Rheumatol, Bad Bramstedt, Germany
[21] Univ Dusseldorf, Dept Dermatol, D-4000 Dusseldorf, Germany
[22] Univ Gottingen, Dept Dermatol & Venerol, Gottingen, Germany
[23] Univ Tubingen, Dept Dermatol, Tubingen, Germany
[24] Univ Tubingen, Dept Internal Med, D-7400 Tubingen, Germany
[25] Heidelberg Univ, Dept Internal Med, D-6900 Heidelberg, Germany
[26] Graz Univ, Dept Dermatol & Venerol, Graz, Austria
[27] Ctr Rheumatol, Dept Internal Med, Baden, Switzerland
[28] Clin Minden, Dept Dermatol, Minden, Germany