1. Institute of Medical Informatics, Biometry and Epidemiology University Hospital Essen Essen Germany
2. Center for Clinical Trials Essen (ZKSE) University Hospital Essen Essen Germany
3. Apogepha Arzneimittel GmbH Dresden Germany
4. Department of Epidemiology, School of Public Health Boston University Boston Massachusetts
5. Department of Pharmacology Johannes Gutenberg University Mainz Germany