1. Department of Pulmonology, Saarland University, Homburg/Saar, Germany
2. Department of Gastroenterology, Saarland University, Homburg/Saar, Germany
3. 1st Department of Medicine, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer, Mannheim, Germany
4. Department of Biometry, Epidemiology and Medical Informatics, Saarland University, Homburg/Saar, Germany