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.