Division of Gastroenterology and Hepatology, Department of Internal Medicine, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands. Electronic address: m.bosman@maastrichtuniversity.nl. Department of Medical Psychology and Medical Sociology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany; Department of Neurology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany. NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, Nottingham, UK; University of Nottingham and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK. Translational Research Center for Gastrointestinal Disorders, Catholic University of Leuven, Leuven, Belgium; Division of Gastroenterology and Hepatology, University Hospitals Leuven, Leuven, Belgium. Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Centre for Functional GI and Motility Disorders, University of North Carolina, Chapel Hill, NC, USA. Department of Methodology and Statistics, Care and Public Health Research Institute, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, Netherlands. Division of Gastroenterology and Hepatology, Department of Internal Medicine, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands.