[1] Heinrich Heine Univ, Univ Hosp Dusseldorf, Hiller Res Ctr, Med Fac, D-40225 Dusseldorf, Germany
[2] Heinrich Heine Univ Dusseldorf, Inst Biometry & Epidemiol, German Diabet Ctr, Dusseldorf, Germany
[3] Univ Witten Herdecke, Chair Med Biometry & Epidemiol, Witten, Germany
[4] Heinrich Heine Univ, Univ Hosp Duesseldorf, Med Fac, Clin Dermatol, Dusseldorf, Germany
[5] Ruhr Univ, St Josef Hosp, Dept Dermatol Venereol & Allergol, Bochum, Germany
[6] Heinrich Heine Univ, Univ Hosp Dusseldorf, Med Fac, Clin Rheumatol, Dusseldorf, Germany
[7] Ruhr Univ Bochum, Rheumazentrum Ruhrgebiet, Herne, Germany