Zsa Zsa Weerts

Chapter 3 52 Hence, the current follow-up study, which is part of a large prospective cohort study on the pheno- and genotypical characterization of IBS in the Netherlands, aimed 1) to gain further insight into symptom evolution and long-term quality of life over a five-year follow-up period; 2) to identify baseline predictors for higher symptom severity and greater quality of life impairment at follow-up; and 3) to assess how point 1 and 2 differ between patients that remain Rome III-positive and those who are Rome III-negative at follow-up. Materials and methods Irritable bowel syndrome cohort study Since 2009, patients with IBS between 18 and 75 years of age who visit the outpatient clinic of the Gastroenterology-Hepatology division of the Maastricht University Medical Center+ (MUMC+), The Netherlands, are requested to enroll in the Maastricht IBS (MIBS) Cohort study. The MUMC+ is a university hospital with a combined secondary and tertiary care service in the area of South Limburg, The Netherlands. In addition, patients with IBS are recruited via general practitioners in the area of South Limburg. The MIBS Cohort is an extensively phenotyped cohort of IBS patients with a follow-up measurement five years after initial inclusion. 15-17 The research protocol had been approved by the MUMC+ Committee of Ethics and all study procedures were performed in compliance with Good Clinical Practice Guidelines and according to the revised Declaration of Helsinki. 18 The study had been registered in the US National Library of Medicine ( NCT00775060 ). All subjects gave a written informed consent prior to participation. Subjects Patients who had been included at least three years (five +/- two years) before the current study, that is, patients included in the MIBS cohort between September 2009 and September 2014, were eligible for participation in the current follow-up study. All patients fulfilled the Rome III criteria for IBS at the time of inclusion, which was confirmed by a trained clinical investigator in a face-to-face interview. Patients were assigned IBS subtypes based on their reported predominant stool-type, i.e. diarrhea (IBS-D), constipation (IBS-C), a mix of diarrhea and constipation (IBS-M), or unspecified predominant bowel habit (IBS-U). Their medical history was taken and, if any alarm symptoms were present or if deemed necessary by the gastroenterologist, GI endoscopy, abdominal imaging, and/or blood, breath and/or fecal analyses were