The Inflammatory Bowel Disease Symptom Inventory: A Patient-report Scale for Research and Clinical Application

Objectives: Existing measures of inflammatory bowel disease (IBD) symptoms are not well suited to self-report, inadequate in measurement properties, insufficiently specific, or burdensome for brief or repeated administration. We aimed to develop a patient-reported outcome measure to assess a broader range of IBD symptoms. Methods: The IBD Symptoms Inventory (IBDSI) was developed by adapting symptom items from existing clinician-rated or diary-format inventories; after factor analysis, 38 items were retained on 5 subscales: bowel symptoms, abdominal discomfort, fatigue, bowel complications, and systemic complications. Participants completed the IBDSI and other self-report measures during a clinic visit. A nurse administered the Harvey Bradshaw Index (HBI) for Crohn's disease (CD) or the Powell-Tuck Index (PTI) for ulcerative colitis (UC), and a gastroenterologist completed a global assessment of disease severity (PGA). Results: The 267 participants with CD (n = 142) or UC (n = 125), ages 18 to 81 (M = 43.4, SD = 14.6) were 58.1% female, with a mean disease duration of 13.9 (SD = 10.5) years. Confirmatory factor analysis supported the 5 subscales. The total scale and subscales showed good reliability and significant correlations with self-report symptom and IBD quality of life measures, the HBI, PTI, and PGA. Conclusions: The IBDSI showed strong measurement properties: a supported factor structure, very good internal consistency, convergent validity, and excellent sensitivity and specificity to clinician-rated active disease. Self-report HBI and PTI items, when extracted from this measure, produced scores comparable to clinician-administered versions. The 38-item IBDSI, or 26-item short form, can be used as a brief survey of common IBD symptoms in clinic or research settings.