ABSTRACT
Irritable bowel syndrome (IBS) is a chronic, oftentimes disabling gastrointestinal disorder
characterized by recurrent abdominal pain associated with alterations in bowel habits (diarrhea
and/or constipation). Three subtypes of IBS have been defined based on stool patterns: IBS
with predominant diarrhea (IBS-D), IBS with predominant constipation (IBS-C), and alternating
or mixed IBS (IBS-M). Approximately 10% to 15% of adults in the United States are affected by
IBS, with IBS-D estimated to account for roughly a third of the cases. Due to the disruptiveness
of the abdominal and bowel movement-related symptoms in their daily lives, IBS is among the
top 10 reasons people consult a primary care physician.
Although several global and symptom-specific PRO measures have been used to support
approval of treatments for IBS, FDA encouraged the development of comprehensive subtype-
specific symptom severity measures that meet its regulatory expectations. The PRO
Consortium formed the IBS Working Group to meet this unmet measurement need. To begin
the development of the Diary for Irritable Bowel Syndrome Symptoms–Diarrhea (DIBSS-D) and
measures for the 2 other subtypes, the IBS Working Group reviewed the literature and
conducted concept elicitation interviews to identify a comprehensive set of symptoms
experienced by people with IBS. Based on these results and input from a patient representative
and advisory panelists, a set of IBS symptoms was identified, and draft items were generated to
assess the core symptoms of each subtype. Then, 3 rounds of cognitive interviews were
conducted with 16 participants with IBS-D to ensure that the DIBSS-D addressed the IBS
symptoms of greatest importance to participants and to optimize the item wording and response
scales. The developmental DIBSS-D was subsequently tested in a cross-sectional observational
study conducted at 10 clinical sites across the US that included 133 participants with IBS-D.
Aim 1 of this proposed project is to analyze the data collected from participants with IBS-D in
our cross-sectional observational study in accordance with the QP and its accompanying
statistical analysis plan currently under QRT review. Aim 2 is to prepare a Full Qualification
Package (FQP) in accordance with the most current version of FDA’s COA FQP content outline,
and Aim 3 is to submit the DIBSS-D FQP to FDA. The intended result of this project will be a
qualified, publicly available PRO measure for the assessment of abdominal and bowel-
movement-related symptom severity in persons with IBS-D. Qualifying the DIBSS-D will fill a
critical gap in the measurement of patient-reported clinical benefit in IBS-D treatment trials.
