1. Institute of Biometry and Epidemiology, The German Diabetes Center, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
2. Department of Rheumatology, St. Elisabeth-Hospital Meerbusch-Lank, Meerbusch, Germany
3. Hiller Research Center, University Hospital Düsseldorf, Medical Faculty of Heinrich Heine University, Düsseldorf, Germany
4. Chair for Medical Biometry and Epidemiology, University of Witten/Herdecke, Witten, Germany