1. Clinic of Internal Medicine III, Department of Oncology, Haematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
2. Clinic of Internal Medicine III, Department of Oncology, Haematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Bonn, Germany
3. Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany
4. Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA