Responsiveness and Interpretation of a Symptom Severity Index Specific to Upper Gastrointestinal Disorders

Background & Aims: Determining clinically meaningful change of patient-reported outcome measures is important for evaluating effectiveness of treatments for gastrointestinal (GI) diseases. This study evaluates responsiveness of the Patient Assessment of Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM) in gastroesophageal reflux disease (GERD) and dyspepsia. Methods: The PAGI-SYM was based on a review of the published literature and interviews with patients and clinicians. Items were developed to be linguistically and culturally appropriate for multicountry studies. The PAGI-SYM includes 6 subscales: heartburn/regurgitation, fullness/early satiety, nausea/vomiting, bloating, upper abdominal pain, and lower abdominal pain. Subjects with GERD (n = 810) or dyspepsia (n = 767) participated in this multicountry, observational study. All subjects completed the PAGI-SYM, a global symptom relief questionnaire, and a measure of patient-rated change in GI-related symptoms, the Overall Treatment Effect (OTE) scale. Responsiveness was evaluated at 8 weeks by comparing groups by disease, symptom relief, and OTE (improved, stable, and worsened). Results: Subjects reporting symptom relief reported significantly lower (better) PAGI-SYM scores than those reporting no symptom relief (P < 0.0001 to P < 0.0005). Subjects with improvements in overall GI symptoms exhibited significant decreases in PAGI-SYM subscale scores compared with those who remained the same or worsened (all P values < 0.0001). Effect sizes ranged from 0.21-1.28, and standard errors of measurement ranged from 0.29-0.63, depending on subscale and disease sample. Conclusions: The PAGI-SYM is a brief symptom severity instrument that measures common GI symptoms. Results suggest that the PAGI-SYM is responsive and sensitive to change in clinical status in subjects with GERD or dyspepsia.