Gastroparesis Cardinal Symptom Index (GCSI): Development and Validation of a Patient Reported Assessment of Severity of Gastroparesis Symptoms

Background: Patient-rated symptom assessments are needed for evaluating the effectiveness of medical treatments and for monitoring outcomes in gastroparesis.

Objective: This paper summarizes the development and psychometric evaluation of a new instrument, the Gastroparesis Cardinal Symptom Index (GCSI), for assessing severity of symptoms associated with gastroparesis.

Methods: The GCSI was based on reviews of the medical literature, patient focus groups, and interviews with clinicians. A sample of 169 patients with a documented diagnosis of gastroparesis participated in the psychometric evaluation study. Patients completed the GCSI, the SF-36 Health Survey, and disability days questions at baseline and after 8 weeks. A randomly selected sub-sample of 30 subjects returned at 2 weeks to assess test retest reliability. Clinicians rated severity of symptoms, and both clinicians and patients rated change in gastroparesis-related symptoms over the 8 week study.

Results: The GCSI is based on three subscales: post-prandial fullness/early satiety (4 items); nausea/vomiting (3 items), and bloating (2 items). Internal consistency reliability was 0.84 for the GCSI total score and ranged from 0.83 to 0.85 for the subscale scores. Two week test retest reliability was 0.76 for the total score and ranged from 0.68 to 0.81 for subscale scores. Construct validity was supported, given that we observed significant relationships between clinician assessed symptom severity and GCSI total score, significant differences between gastroparesis and dyspepsia patients (n = 760) on GCSI total (p < 0.0001) and subscale scores (p < 0.03 to p < 0.0001), moderate and significant relationships between GCSI total and SF-36 scores, and significant associations between GCSI total score and reports of restricted activity and bed disability days. Patients with greater symptom severity, as rated by clinicians, reported more symptom severity on GCSI total score. GSCI total scores were responsive to changes in overall gastroparesis symptoms as assessed by clinicians (p < 0.0001) and patients (p = 0.0004).

Conclusion: The findings of this study indicate that the GCSI is a reliable and valid instrument for measuring symptom severity in patients with gastroparesis.