1. Institute of General Practice and Family Medicine, Medical Faculty, University of Bonn, Bonn, Germany;
2. Department of Palliative Medicine, University Hospital Bonn, Bonn, Germany;
3. General Medicine, Teaching Area RWTH Aachen University, Aachen, Germany;
4. Institute of General Practice, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany;
5. Department of General Practice, Medical Faculty, Ruhr University of Bochum, Bochum, Germany;
6. Institute for General Medicine, University of Duisburg-Essen, Essen, Germany