S1245 ROME III Subtyping Is Associated with Alterations in Intestinal Motility and Secretion, But Not with Sensitivity or Psychosocial Factors

Abstract

Background: Visceral hypersensitivity, altered gastrointestinal motility and secretion, and psychosocial factors are considered to be of great importance for the symptom pattern in irritable bowel syndrome (IBS). The Rome III criteria propose subtyping of IBS patients based on stool form alone (Longstreth et al Gastroenterology 2006), but the association with the underlying pathophysiology is unknown. Aim: To evaluate the link between pathophysiological factors and Rome III subtyping. Methods: We included 129 IBS patients (96 females, 33 males; mean age 37 (19-67) years). The patients were subtyped according to the Rome III criteria based on one-week diaries, where the stool form (Bristol Stool Form scale) was reported. All patients underwent investigations to assess colonic motility (colonic transit time), small intestinal motility and secretion (antroduodenojejunal manometry with jejunal transmural potential difference (PD) measurement) and rectal sensorimotor function (rectal balloon distensions before and after meal intake). The patients also completed questionnaires to assess the severity of psychological, gastrointestinal and extraintestinal symptoms. Results: Fifty-five patients had IBS-D (diarrhea), 29 IBS-C (constipation), 11 IBS-M (mixed) and 34 IBS-U (unsubtyped). For the analyses M+U was combined into one group (“NonCNonD”). Colonic transit time differed between the subgroups (p<0.0001), with slower transit in IBS-C (1.8±2.9 (mean±SD) days), faster in IBS-D (1.0±1.4 days), and intermediate in the NonCNonD-group (1.4±2.0 days). There were also group differences in small intestinal motility, with higher contraction frequency in the fasted state (p<0.05), longer phase III duration (p<0.01) and faster propagation velocity of phase III (p<0.01) in IBS-D. The small intestinal secretion during phase III (mean PD × length of the secreting segment, calculated from duration and propagation velocity) also differed between the subtypes, with enhanced secretion in IBS-D (p<0.001). Also the mean fasted PD tended to be higher in IBS-D (p<0.05). Rectal sensitivity, compliance and the rectal tone response, as well as psychological or extraintestinal symptom severity was similar in the subtypes. The perceived severity of constipation (p<0.01) and diarrhea (p<0.01), but not other GI symptoms, also differed between the subtypes. Conclusion: Subtyping of IBS patients based on the stool form is associated with alterations small intestinal and colonic motility, as well as small intestinal secretion. However, other pathophysiological factors, as well as symptoms other than constipation and diarrhea, seem unrelated to the different Rome III-based IBS subtypes.