Increased Disease Burden in Irritable Bowel Syndrome With Comorbid Conditions and Psychiatric Diagnoses in a Multinational European Cohort: Results From the DISCOvERIE Project

Background: Patients with Irritable bowel syndrome (IBS) frequently suffer from comorbid psychiatric or somatic conditions, but the association with overall GI symptom severity and disease burden in IBS has not yet been established. Objective: This pan-European project, the DISCOvERIE project, aimed to characterize IBS patients with and without comorbid psychiatric (anxiety, depression) and/or somatic (fibromyalgia, chronic fatigue syndrome) conditions, and to compare them with disease (psychiatric and/or somatic condition without IBS) and healthy controls to further elucidate the effect of comorbid conditions on the disease burden in IBS. Methods: Participants from nine different European centers were included: IBS patients (Rome IV criteria) with and without comorbid conditions, disease controls, and healthy controls. The presence of comorbidities was assessed through the Mini International Neuropsychiatric Interview (MINI) for anxiety or depression or through diagnostic criteria for fibromyalgia or chronic fatigue syndrome. Validated questionnaires on IBS (IBS-SSS), depressive (PHQ-9), anxiety (GAD-7) and somatic symptom severity (PHQ-12), fibromyalgia symptoms (FIQ) and fatigue (MFI) were completed. Results: In total, 842 participants were recruited between March 2021 and January 2023, of which 607 had IBS, 161 were disease controls and 74 were healthy controls. IBS, anxiety, depression, somatic symptoms and fatigue were more severe in IBS patients with comorbidities compared with IBS patients without comorbidities. The severity of the abovementioned symptoms all increased gradually with increasing number of comorbidities (all p < 0.001). Conclusion: This large pan-European study highlights the significant impact of psychiatric and somatic comorbidities in IBS, and their strong link with outcomes and disease burden.