The American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index—Daily Diary (ANMS GCSI—DD): Psychometric Evaluation in Patients With Idiopathic or Diabetic Gastroparesis: Category Award (Stomach): Presidential Poster Award

Abstract

Introduction: The ANMS GCSI—DD was developed to meet FDA recommendations for use as a Patient Reported Outcome endpoint for therapeutic trials in gastroparesis. The purpose of this study was to evaluate the psychometric measurement properties (reliability and validity) of the five—item ANMS GCSI—DD in idiopathic (IG) or diabetic gastroparesis (DG).1217_A Figure 1. Study Visit Procedures and Assessments1217_B Figure 2. Psychometric Evaluation Results for ANMS GCSI—DD total scoreMethods: Patients diagnosed with IG or DG were recruited by 10 clinical sites in the United States for a longitudinal, four—week, observational study consisting of visits at Baseline and Week 4. Patients and clinicians completed a series of paper case report forms at both visits (Table 1). Patients were asked to complete the paper ANMS GCSI—DD at home for approximately 4 weeks in between visits. The ANMS GCSI—DD assesses nausea, early satiety, postprandial fullness, and upper abdominal pain on a severity score from none (0) to very severe (4) and the number of vomiting episodes during the past 24 hours. A symptom composite score is the average of these five gastroparesis symptoms. Statistical analyses using SAS included test—retest reliability, internal consistency reliability, concurrent validity, and known groups validity. Test—retest reliability was assessed from Baseline to Week 4 in stable patients with no change in patient global impression of severity (PGI—S). Internal consistency reliability, concurrent validity, and known groups validity were assessed at Baseline and Week 4. Results: 71 patients were enrolled, 45 IG and 26 DG. At Baseline, mean ANMS GCI—DD symptom composite scores were 1.44 ± 0.77 (range 0—3). The mean score change from Baseline to Week 4 was —0.12 ± 0.39 (range —1.71—0.60). Cronbach's alpha for internal consistency was 0.83 for the ANMS GCI—DD symptom composite score (Table 2). Test—retest reliability was 0.88. Convergent validity was supported by strong correlations with the Patient—Reported Outcomes Measurement Information System (PROMIS) global physical health rating (—0.53) and PGI—S (0.62). Baseline and Week 4 scores differed by PGI—S group (p<0.0001), supporting known groups validity. Conclusion: The ANMS GCSI—DD has excellent reliability and validity as a symptom composite score and for individual gastroparesis symptoms in patients with either IG or DG supporting its use as a PRO for clinical studies. Further analyses will be conducted using clinical trial data to confirm the instrument's measurement properties and to develop a responder definition for patients with IG or DG.