1. Institute for Biomedical Informatics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany
2. Institute for Medical Informatics, Statistics and Epidemiology (IMISE), Leipzig University, Germany
3. Fraunhofer Institute for Applied Information Technology (FIT), Germany and Information Systems and Database Technology Research Group, RWTH Aachen University, 52062 Aachen, Germany, Germany
4. Institute for Biomedical Informatics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany and Fraunhofer Institute for Applied Information Techniques (FIT), Germany