1. Practice Centre Rethen, Centre for General Medicine, Academic Teaching Practice of Hannover Medical School , Hannover , Germany
2. Department of Diagnostic and Interventional Radiology , Hannover Medical School , Hannover , Germany
3. Department of General Surgery , University Hospital Basel , Basel , Switzerland
4. Department of General Surgery , Hospital Hildesheim, Academic Teaching Hospital of Hannover Medical School , Hannover , Germany
5. Department of Medical Statistics and Biometry , Medical Faculty Carl Gustav Carus at Technical University Dresden , Dresden , Germany
6. Department for Internal Medicine I , University Hospital Halle/Saale , Halle/Saale , Germany