1. Department of Neurology, University Hospital of Essen, University of Duisburg-Essen, Essen, Germany
2. Department of Hematology, University Hospital of Essen, University of Duisburg-Essen, Essen, Germany
3. Department of Endocrinology, Division of Laboratory Research, University Hospital of Essen, University Duisburg-Essen, Essen, Germany
4. Institute for Medical Sociology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
5. Institute for Medical Informatics, Biometry and Epidemiology, University Hospital of Essen, University Duisburg-Essen, Essen, Germany
6. Clinic of Cardiology, West German Heart Centre, University Hospital of Essen, University Duisburg-Essen, Essen, Germany