Development of the Diary for Irritable Bowel Syndrome Symptoms to Assess Treatment Benefit in Clinical Trials: Foundational Qualitative Research
BACKGROUND: Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder characterized by abdominal pain and alterations in bowel habits. Three subtypes are defined on the basis of stool patterns: diarrhea-predominant IBS, constipation-predominant IBS, and alternating or mixed IBS.
OBJECTIVES: To develop patient-reported outcome measures for qualification by the Food and Drug Administration to support product approvals and labeling in IBS; the article focuses on the qualitative research that provided the foundation for the new measures.
METHODS: Forty-nine concept elicitation and 42 cognitive debriefing interviews were conducted with subjects meeting Rome III criteria; additional criteria were imposed to yield a sample representative of the target patient population.
RESULTS: Although incomplete bowel movements, abnormal stool frequency and consistency, and abdominal pain, discomfort, and bloating were reported most frequently across concept elicitation interviews, the relative importance of specific symptoms varied by subtype. Among their five symptoms most important to treat, diarrhea-predominant and alternating or mixed IBS subjects frequently identified urgency, loose/watery stools, abdominal pain, and cramping, whereas constipation-predominant IBS subjects commonly included infrequent and incomplete bowel movements, bloating, and abdominal pain. The cognitive debriefing interviews facilitated refinement of each item set, supported minor modifications following translatability assessment, and suggested improvements to the electronic interface. Furthermore, subjects reported that every item was relevant and no concepts of importance were missing.
CONCLUSIONS: Results support the content validity of the IBS patient-reported outcome measures. A pilot study was recently initiated to inform item reduction, develop scoring algorithms, and provide preliminary psychometric information. Comprehensive psychometric evaluation and responder definition development will follow.