Evaluating the ANMS GCSI-DD: a reliable patient-reported tool to measure symptom change in moderate-to-severe gastroparesis

Aims: The American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index–Daily Diary (ANMS GCSI-DD) is a patient-reported outcome (PRO) instrument designed to assess gastroparesis symptoms. This study aims at evaluating its psychometric properties and establish a threshold for meaningful change, using data from a Phase 2b clinical trial with adults suffering from moderate-to-severe idiopathic or diabetic gastroparesis.

Methods: 242 participants (55.7 y, M/F: 59/183, T2D 96, T1D 18) were evaluated over 12 weeks and enrolled in a multicentre, randomized, double-blind, placebo-controlled, Phase 2b trial evaluating the efficacy and safety of twice-daily oral trazpiroben, a peripherally acting dopamine receptor D2/D3 antagonist. Participants completed the ANMS GCSI-DD daily on an electronic device, along with other PRO measures like PAGI-SYM, PAGI-QoL, PGI-S, PGI-C, PGI-I, and OTE-S. Clinicians also provided ratings via the Clinical Symptom Severity Rating (CSSR) and OTE-C. Eligible patients had at least 3 months of gastroparesis symptoms and confirmed delayed gastric emptying. They were randomized to receive either trazpiroben (5, 25, or 50 mg) or placebo for 12 weeks.

Results: The evaluation focused on unidimensionality (using confirmatory factor analysis and item response theory), internal consistency, test-retest reliability, construct validity, known-groups validity, and responsiveness to symptom change. PRO and clinician-reported outcomes were used as anchors to evaluate the instrument’s validity and responsiveness, and to establish a meaningful change threshold. The ANMS GCSI-DD exhibited strong psychometric properties. Unidimensionality analyses showed good model fit, internal consistency reliability exceeded 0.70, and test-retest reliability was above 0.90. Convergent validity demonstrated strong correlations with overall symptom severity ratings (0.70–0.90) and moderate correlations (0.30–0.70) with other measures. The instrument was able to distinguish between groups with varying symptom severity and was responsive to symptom improvement. A one-point change on the five-point scale (0–4) was established as a meaningful change threshold, supported by both quantitative anchor-based estimates (0.9–1.4 points) and qualitative exit interview results (0.5–1.5 points).

Conclusions: The ANMS GCSI-DD is a valid and reliable PRO tool for clinical research involving patients with moderate-to-severe idiopathic or diabetic gastroparesis. A one-point change in the composite score is recommended as a meaningful threshold for evaluating symptom improvement.

Comments: ANMS GCSI-DD was developed from the original two-week GCSI questionnaire, including a 24-h recall period and symptoms of upper abdominal pain and addressing US FDA recommendations for a symptom-based clinical trial endpoint in gastroparesis. This study evaluates the psychometric properties of the ANMS GCSI-DD in the setting of a clinical trial, confirming its reliability and validity for patients with moderate-to-severe diabetic or idiopathic gastroparesis, and also establishing a meaningful change threshold, which is crucial to interpret clinical trial outcomes. Moreover, the inclusion of trial exit interviews in a subgroup of 32 patients adds a qualitative dimension regarding the patient's perspective on this complication. Despite the strengths, replicating the study’s methods in real-world clinical practice could be challenging.

Ilenia D’Ippolito

Reference: Chen YJ, Coyne KS, Rodriguez D, Schulz A, Huh SY, Kuo B, Camilleri M, Tack J, Parkman HP. 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. Neurogastroenterol Motil. 2025 Jan;37(1):e14960. doi: 10.1111/nmo.14960. Epub 2024 Nov 11. PMID: 39529442.

🔗https://onlinelibrary.wiley.com/doi/10.1111/nmo.14960