1. Institute for Medical Informatics, Biometry, and Epidemiology, University of Duisburg-Essen, Essen, Germany
2. Institute of Medical Sociology, University of Düsseldorf, Düsseldorf, Germany
3. Institute of Medical Epidemiology, Biometry, and Informatics, Martin-Luther-University of Halle-Wittenberg, Halle, Germany
4. West German Heart Center Essen, University of Duisburg-Essen, Essen, Germany
5. Rhenish Institute for Environmental Research at the University of Cologne, Cologne, Germany
6. Department of Endocrinology and Division of Laboratory Research, University of Duisburg-Essen, Essen, Germany