Urgency as an Endpoint in Irritable Bowel Syndrome

BACKGROUND The choice of endpoints is crucial for proper evaluation of agents in clinical trials of irritable bowel syndrome (IBS). In a recently published draft guidance for IBS from the United States Food and Drug Administration (FDA), urgency was not considered an appropriate primary endpoint. The FDA's position is that it is not clear how patients with diarrhea-predominant IBS (D-IBS) "define or describe urgency". The aims of this study were to evaluate the association of urgency with stool frequency and consistency in patients with D-IBS and to describe results from patient interviews on their understanding of the term urgency. METHODS A retrospective analysis of clinical trial data in patients with D-IBS was conducted. Analyses focused on the relationship of urgency to stool frequency and consistency. Interviews were conducted with patients with D-IBS to test their understanding of the term urgency. RESULTS On the days that patients reported urgency, as compared to the days that patients did not report urgency, they had more frequent bowel movements (3.9 versus 1.8) and looser stools (Bristol Stool Score: 5.4 versus 4.2). The differences for both parameters, evaluated on the days with or without urgency, were statistically significant. In patient interviews, patients with D-IBS had a clear understanding of the concept and terminology of urgency and considered it one of their two most bothersome symptoms. CONCLUSIONS Urgency should be considered a suitable co-primary endpoint in D-IBS studies.