Modified Severity of Dyspepsia Assessment pain scale: a new tool for measuring upper abdominal pain in osteoarthritis patients taking NSAIDs

BACKGROUND: This study evaluated the electronically administered modified Severity of Dyspepsia Assessment (mSODA) pain scale, a six-item measure of upper abdominal pain intensity, for daily use in osteoarthritis patients taking nonsteroidal anti-inflammatory drugs. METHODS: Once the mSODA pain scale was isolated, cognitive debriefing interviews (n = 30) were used to examine its appropriateness in the target population. Following administration of the instrument in two Phase III pivotal trials, the data were analyzed to examine reliability, validity, responsiveness, and the minimal important difference. RESULTS: Using a subset of trial data (n = 90 patients), the mSODA pain scale proved to be a unidimensional, highly internally consistent instrument (α = 0.93) with good test-retest reliability (intraclass correlation coefficient 0.77). Construct validity was established via moderate correlations with other similar patient-reported outcomes. Additionally, known-groups validity demonstrated that the mSODA pain scale could distinguish between subjects who did and did not report gastrointestinal symptoms and antacid use (both P values ≤ 0.05). The mSODA pain scale was also responsive to change in heartburn at weeks 6 and 12 (Guyatt’s statistic = 1.7 and 2.6, respectively), and the minimal important difference obtained via ½ SD was 5.7 (range 2–47). CONCLUSION: This research suggests that the mSODA pain scale is both feasible and valid for assessing dyspepsia in patients taking nonsteroidal anti-inflammatory drugs for relief of symptoms of osteoarthritis.