1. Department of Rheumatology and Clinical Immunology, Charité – Universitätsmedizin Berlin
2. Department of Rheumatology, Clinical Immunology and Nephrology, Asklepios Klinik Altona, Hamburg, Klinikum Bad Bramstedt, Germany
3. Division of Rheumatology, University Hospital Hamburg-Eppendorf, Hamburg and Klinikum Bad Bramstedt, Bad Bramsted, Germany