1. Clinical Epidemiology Unit, Institute of Medical Epidemiology, Biometry, and Informatics, Martin-Luther-University of Halle-Wittenberg, Sachsen-Anhalt, Germany
2. Institute of Medical Informatics, Biometry, and Epidemiology, University of Duisburg-Essen, Duisburg-Essen, Germany
3. Clinic of Cardiology, West German Heart Center, University of Duisburg-Essen, Duisburg-Essen, Germany