1. I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Internal Medicine, Gastroenterology, Hepatology, Endoscopy and Diabetology, Osnabrück, Germany
3. Institute of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Department of Interdisciplinary Endoscopy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
5. Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
6. III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany