Patient-based assessment in dyspepsia: development and validation of Dyspepsia Symptom Severity Index (DSSI)

This paper describes the development and testing of a new self-report measure, the Dyspepsia Symptom Severity Index (DSSI), for assessing the severity of symptoms commonly associated with dyspepsia. The instrument was based on the literature, focus groups, and feedback from gastroenterologists; 48 patients and 24 controls participated in testing. Patients completed the DSSI and a symptom diary to test concurrent validity; one-week reproducibility was evaluated in 21 stable patients. Three subscales comprise the 20-item DSSI, representing reflux-, ulcer-, and dysmotility-like symptoms. Subscale internal consistency levels (alpha) were high (0.84-0.89), total score alpha levels were very good (0.76, 0.80), and scores were reproducible (ICC = 0.90-0.92). Correlations between the DSSI and diary were moderate to strong (r = 0.33-0.77; P < 0.05). Patients reported significantly more severe symptoms than controls (P < 0.001). Results indicate the DSSI is a reliable and valid tool for evaluating symptom severity in patients with functional dyspepsia.