The American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index‐Daily Diary (ANMS GCSI‐DD): Psychometric validation and meaningful change threshold in patients with idiopathic or diabetic gastroparesis

Abstract Introduction The American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index‐Daily Diary (ANMS GCSI‐DD) is a patient‐reported outcome (PRO) instrument for gastroparesis. This study evaluated the psychometric properties of the ANMS GCSI‐DD and determined a meaningful change threshold using the data from a phase 2b trial in adults with moderate‐to‐severe idiopathic or diabetic gastroparesis (DG). Methods The psychometric properties of ANMS GCSI‐DD were analyzed using other clinician‐ and patient‐reported outcomes from 242 patients during the 12‐week trial. Trial exit interviews were conducted in a cohort of 32 patients to capture their perspectives on meaningful change from the trial. Results ANMS GCSI‐DD demonstrated good performance: unidimensionality scores exhibited good fit; internal consistency reliability was >0.70; test–retest reliability was above 0.90, and convergent validity showed strong correlations (0.70–0.90) with overall severity rating and moderate correlations (0.30–0.70) with other outcomes. ANMS GCSI‐DD scores discriminated among groups with varying severity of gastroparesis symptoms in known‐groups validity ( p < 0.001) and were responsive to symptom improvement. Triangulation of the quantitative anchor‐based estimates of 0.9–1.4 category points as a meaningful change in the ANMS GCSI‐DD composite score, and the qualitative exit interview findings of 0.5–1.5 as meaningful change, supports a one‐point change on a five‐point scale (0–4) as the meaningful change threshold. Conclusion The ANMS GCSI‐DD is a reliable and valid PRO instrument to employ in clinical development for patients with moderate‐to‐severe idiopathic or DG, and a one‐point score change in the ANMS GCSI‐DD composite score is recommended as a meaningful change threshold of symptom change.