Overlap of Rome IV Irritable Bowel Syndrome and Functional Dyspepsia and Effect on Natural History: A Longitudinal Follow-Up Study

OBJECTIVES: Disorders of gut-brain interaction, such as irritable bowel syndrome (IBS) and functional dyspepsia (FD), frequently overlap, but the impact of this on the natural history is unknown. We examined this issue in a longitudinal follow-up study conducted in a large cohort of individuals. METHODS: We collected complete demographic, symptom, mood, and psychological health data from 1374 adults who self-identified as having IBS. We applied the Rome IV criteria to examine what proportion met criteria for IBS and FD, as well as the degree of overlap between them. At 12 months, we collected data regarding IBS symptom severity and impact, consultation behavior, treatments commenced, and psychological health according to degree of overlap between IBS and FD. RESULTS: Overall, 807 individuals met the Rome IV criteria for IBS at baseline and provided complete data. At study entry, overlap of FD occurred in 446 (55.3%) people who met Rome IV criteria for IBS. At 12 months, 451 (55.9%) individuals were successfully followed up. The proportion of individuals consulting their primary care physician (P = .001) or a gastroenterologist (P < .001) because of their IBS was significantly higher in those with overlap of IBS and FD, and the number of new IBS treatments commenced was significantly higher (P = .007). Those with overlap of IBS and FD reported significantly more severe IBS symptoms (P < .001), continuous abdominal pain, and that their IBS symptoms limited normal daily activities >= 50% of the time. Finally, those with overlap were more likely to report abnormal anxiety and depression scores at 12 months compared with those with IBS alone, and to have higher levels of somatization (P < .001 for all analyses). CONCLUSIONS: The natural history of people with IBS with overlap FD defined according to Rome IV criteria is more severe than those with IBS alone. This has important implications for future treatment trials in IBS.