1 K. Minden, MD, Epidemiology Unit, German Rheumatism Research Center Berlin, a Leibniz Institute, and Department of Rheumatology and Clinical Immunology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin; minden@drfz.de.
2 J. Klotsche, PhD, Epidemiology Unit, German Rheumatism Research Center Berlin, a Leibniz Institute, Berlin, Germany.