Qualitative and psychometric evaluation of the PROMIS®-Fatigue SF-7a scale to assess fatigue in patients with moderately to severely active inflammatory bowel disease

Abstract

BackgroundThis study evaluated the content validity and psychometric properties of the Patient-Reported Outcomes Measurement Information System® (PROMIS)-Fatigue Short Form 7a (SF-7a) v1.0 scale to determine its suitability in clinical trials to assess fatigue in patients with moderately to severely active Crohn’s disease (CD) and ulcerative colitis (UC).MethodsA qualitative interview assessed patients’ experience living with CD (N = 20) and UC (N = 19). The contents of the SF-7a scale were cognitively debriefed to evaluate content validity. A psychometric evaluation was performed using data from clinical trials of patients with CD (N = 360) and UC (N = 214). Correlations with Inflammatory Bowel Disease Questionnaire (IBDQ), Crohn’s Disease Activity Index (CDAI; CD only), and Mayo score (UC only) determined validity. The Patient Global Impression of Change (PGIC) was used to evaluate reliability and responsiveness to change. Using PGIC as an anchor, a preliminary threshold for clinically meaningful change was identified to define fatigue response in both CD and UC patients.ResultsAll patients reported fatigue as a common symptom. Patients confirmed SF-7a items were relevant to assessing fatigue, instructions and response options were clear, and its 7-day recall period was appropriate. Higher SF-7a scores were associated with higher disease activity (CDAI and Mayo score) and lower health-related quality of life (IBDQ), confirming known groups validity. The correlation of the SF-7a scale was higher with fatigue-related items. (rs ≥ -0.70) than with items not directly associated with fatigue. Test-retest reliability was moderate to good (0.54–0.89) among patients with stable disease, and responsiveness to change in disease severity was demonstrated from baseline to Week 12. A ≥7point decrease was identified as a reasonable threshold to define clinically meaningful improvement.ConclusionThe SF-7a scale is a valid, reliable, and sensitive measure of fatigue in patients with moderately to severely active IBD and can be used to evaluate treatment response.