OBJECTIVES: 1) Identify a comprehensive set of symptoms experienced by patients with irritable bowel syndrome with constipation (IBS-C), and 2) Identify the most important symptoms for measurement in clinical trials for IBS-C.
METHODS: Two iterative sets of in-depth interviews were conducted in different US cities, with a total of 27 participants meeting modified Rome II criteria for IBS-C. A semi-structured interview guide was used, beginning with a series of open-ended questions to elicit all relevant symptoms, followed by interviewer probes to fully understand the relationships among the concepts. Multiple rating and ranking methods were used to develop a subset of IBS-C symptoms of greatest importance to patients. For example, participants were asked to identify their most bothersome IBS-C symptoms, as well as those in which they would most like to see an improvement with treatment.
RESULTS: When asked to describe their IBS-C symptoms, patients reported 54 potentially distinct concepts: 8 abdominal symptoms, 12 bowel symptoms, 31 additional physical symptoms (e.g., nausea, headache), and 3 emotional issues (e.g., irritability, depression). Some symptom terms were highly related (e.g., abdominal pain and stomach ache) and others could be considered consequential to IBS-C (e.g., hemorrhoids, vomiting). Results of the subsequent rating and ranking tasks suggest that abdominal pain, abdominal discomfort, bloating, stool frequency, stool consistency, straining, and incomplete evacuation were distinct and represent patients’ most bothersome symptoms. Further, according to the patients, improvements in these symptoms would constitute an improvement in IBS-C overall.
CONCLUSIONS: Patient input is vital to identify the full spectrum of symptoms and to determine an optimal set of clinical trial endpoints. Within and across the two separate rounds of interviews, participants consistently reported the importance of abdominal pain, abdominal discomfort, bloating, stool frequency, stool consistency, straining, and incomplete evacuation, demonstrating concept saturation and supporting the measurement of these symptoms in IBS-C clinical trials.
