1. Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin
2. Department of Epidemiology, German Rheumatism Research Centre, Berlin
3. Department of Epidemiology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal
4. Institute of Public Health, Charité Universitätsmedizin Berlin, Berlin
5. Department of Internal Medicine and Rheumatology, Klinikum Bielefeld Rosenhöhe, Bielefeld, Germany