Minimally Important Differences of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument

OBJECTIVE: To provide minimally important difference (MID) estimates for the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract 2.0 (UCLA SCTC GIT 2.0) in a longitudinal observational cohort. METHODS: We administered the UCLA SCTC GIT 2.0 to 115 patients with systemic sclerosis (SSc) at 2 timepoints 6 months apart. The UCLA SCTC GIT 2.0 has 7 multi-item scales: Reflux, Distension/Bloating, Diarrhea, Fecal Soilage, Constipation, Emotional Well-being, and Social Functioning and a total GIT score. All scales are scored from 0 [better health-related quality of life (HRQOL)] to 3 (worse HRQOL) except the diarrhea and constipation scales (ranges 0–2 and 0–2.5, respectively). Patients also rated their overall and upper and lower GIT involvement during the second visit using a response scale with options "much better; somewhat better; almost the same; somewhat worse; or much worse." The minimally changed group was defined by those reporting they were somewhat better or somewhat worse compared to first visit. RESULTS: Study participants were 84% female and 81% white with a mean disease duration of 6.9 years. The MID estimates for improvement ranged from 0.07 for the Social Functioning scale to 0.36 for the Emotional Well-being scale. For worsening, the MID estimates ranged from 0.06 for the Fecal Soilage scale to 0.21 for the Social Functioning scale. CONCLUSION: We provide MID estimates for the UCLA SCTC GIT 2.0 scales. This information can aid in interpreting scale scores in future randomized controlled trials and observational studies.