Psychometric evaluation of the Functional Assessment of chronic illness therapy-fatigue (FACIT-Fatigue) in adults with moderately to severely active Crohn's disease.

Purpose: To provide further evidence on the psychometric properties of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) in moderately to severely active Crohn's disease (CD), and to determine thresholds for meaningful improvement in fatigue.

Methods: The FACIT-Fatigue is a 13-item patient-reported outcome measure (range, 0-52) assessing fatigue over the previous week. Using pooled data from the Phase 3 VIVID-1 study of moderately to severely active CD, psychometric properties of FACIT-Fatigue were evaluated up to Week 52. The Patient Global Rating of Severity (PGRS) and Patient Global Impression of Change (PGIC) were used as primary anchors to estimate the FACIT-Fatigue score change representing meaningful improvement.

Results: Psychometric analyses included 1065 adults. The FACIT-Fatigue demonstrated good internal consistency, and correlations between individual items and the total score were moderate to strong. The FACIT-Fatigue score showed moderate to strong correlations with other patient-reported assessments and weak correlations with endoscopic/laboratory assessments. The FACIT-Fatigue differentiated between distinct groups of participants varying in disease severity, quality of life, and fatigue based on PGRS and other assessments. FACIT-Fatigue improvements during the study differed significantly between most PGRS change and PGIC categories. Anchor-based estimates suggested a 6-9-point increase in the FACIT-Fatigue total score as meaningful improvement.

Conclusions: The FACIT-Fatigue demonstrated strong psychometric properties in the VIVID-1 population of adults with moderately to severely active CD and determined a FACIT-Fatigue score change threshold representing meaningful improvement.

Trial registration: NCT03926130. Registered 23 April 2019, https://clinicaltrials.gov/study/NCT03926130 .