Alternative Gastrointestinal Conditions Identified in Patients Meeting Rome IV Criteria for Irritable Bowel Syndrome or Functional Diarrhea Referred to Secondary Care: A Prospective Study

Introduction: Organic gastrointestinal (GI) disorders can be missed in individuals with irritable bowel syndrome (IBS). This study investigated the frequency of organic disorders in patients with diarrhea-predominant IBS or functional diarrhea and the impact of treatment for any identified alternative diagnoses. Methods: Between April 2019 and March 2020, the results of comprehensive investigations, including blood and fecal tests, a 75selenium homophobic acid taurine scan, a breath test, and endoscopies performed on consecutive eligible patients, were recorded. Symptom burden was reassessed after treatment for any GI conditions identified. Results: 66 (15 males) consecutive patients were included. Two patients (3%) were diagnosed with colonic malignancy; 21 (38%) had bile acid diarrhea; one (1%) had pancreatic exocrine insufficiency; and 31 (54%) had small intestinal bacterial overgrowth. 21 patients (32%) had at least two GI diagnoses. Significant improvement in symptoms occurred following treatment (p<0.0001). Conclusions: Multiple co-existing conditions were detected in many of these patients, with one-third of the cohort having more than one abnormal test. When these alternative diagnoses were treated, patients reported significant symptomatic improvement. Larger studies are required to validate our findings, and these patients' investigative and management pathways should be amended accordingly.