1. Institute of Clinical Epidemiology, Medical Faculty, University of Halle-Wittenberg, Halle, Germany
2. Institute of Medical Informatics, Biometry and Epidemiology, Medical Faculty, University of Duisburg-Essen, Essen, Germany
3. West German Heart Centre, Medical Faculty, University of Duisburg-Essen, Essen, Germany
4. Cardioangiologisches Centrum Bethanien, Frankfurt, Germany