Development of the NIH Patient-Reported Outcomes Measurement Information System (PROMIS) Gastrointestinal Symptom Scales

OBJECTIVES: The National Institutes of Health (NIH) Patient-Reported Outcomes Measurement Information System (PROMIS(®)) is a standardized set of patient-reported outcomes (PROs) that cover physical, mental, and social health. The aim of this study was to develop the NIH PROMIS gastrointestinal (GI) symptom measures. METHODS: We first conducted a systematic literature review to develop a broad conceptual model of GI symptoms. We complemented the review with 12 focus groups including 102 GI patients. We developed PROMIS items based on the literature and input from the focus groups followed by cognitive debriefing in 28 patients. We administered the items to diverse GI patients (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), systemic sclerosis (SSc), and other common GI disorders) and a census-based US general population (GP) control sample. We created scales based on confirmatory factor analyses and item response theory modeling, and evaluated the scales for reliability and validity. RESULTS: A total of 102 items were developed and administered to 865 patients with GI conditions and 1,177 GP participants. Factor analyses provided support for eight scales: gastroesophageal reflux (13 items), disrupted swallowing (7 items), diarrhea (5 items), bowel incontinence/soilage (4 items), nausea and vomiting (4 items), constipation (9 items), belly pain (6 items), and gas/bloat/flatulence (12 items). The scales correlated significantly with both generic and disease-targeted legacy instruments, and demonstrate evidence of reliability. CONCLUSIONS: Using the NIH PROMIS framework, we developed eight GI symptom scales that can now be used for clinical care and research across the full range of GI disorders.