This study sought to identify the most important and relevant gastrointestinal (GI) symptoms experienced by patients with Fabry disease (FD) and the best way to measure GI symptoms in clinical trials of new treatments for FD. A targeted literature review on GI symptoms relevant in FD for measurement was completed. Qualitative interviews with open-ended concept elicitation and cognitive debriefing were conducted in individuals with FD to explore the relevance of GI symptoms from the patient perspective and to evaluate the content validity of the Diary of Irritable Bowel Syndrome Symptoms—Mixed (DIBSS-M) in the FD population. In the literature review, a high degree of variability of GI symptoms was reported abdominal pain and altered bowel function were most common. Diarrhea was more common in males constipation in females. Additionally, discomfort, bloating and early satiety were frequently noted. Except for early satiety, all these symptoms are addressed in the DIBSS-M. Interviews were conducted in 17 patients diagnosed with FD (13 male, 4 female) ≥ 16 years old mean age of 40.9 years (15.0) in the United States. The most commonly reported symptoms were diarrhea (94% n=16), abdominal pain (64% n=11), bloating (47.1% n=8), and vomiting (41.2% n=7). While nausea is not included on the DIBSS-M, 47.1% of patients found it relevant to their FD. In contrast to the literature, interviewees infrequently noted constipation (5.9% n=1). Patients reported substantial limitation of social and work activities. Patients found the DIBSS-Measy to understand and answer, with an appropriate recall period and distinct options for each question. 88% of patients found the items measured on DIBSS-M to be relevant, especially those about stool frequency, stool consistency, urgency, and abdominal pain. Results support use of the DIBSS-M in clinical studies for FD with a focus on improvements in abdominal pain and altered bowel functioning.
