PROMIS Fatigue short forms are reliable and valid in adults with rheumatoid arthritis

BACKGROUND: Fatigue is prevalent and impactful in rheumatoid arthritis (RA). There is no standardized measure for its assessment nor data concerning the performance of PROMIS-Fatigue short forms (SFs) in people with RA. We evaluated the construct validity of 4-, 7-, and 8-item PROMIS-Fatigue SFs in RA patients across the range of disease activity. METHODS: Adult RA patients were recruited from an online patient community and an observational cohort from three academic medical centers. Measures included PROMIS-Fatigue SFs, other PROMIS measures, and other patient reported outcomes including RAND-36 Vitality, Fatigue NRS, and patient global assessment of disease activity. Other measures from the observational cohort included 28-joint swollen and tender joints, physician global assessment, and the composite RA clinical disease activity index (CDAI). RESULTS: Two-hundred online participants and 348 participants from the observational cohort were included. PROMIS Fatigue SF scores spanned the measurement continuum and correlated highly with each other (r’s ≥ 0.91) and other fatigue measures (r’s ≥ 0.85). PROMIS-Fatigue SF scores were highly and inversely associated with Physical Function and Participation (r’s − 0.77 to − 0.78), and moderately-highly and positively correlated with pain, sleep disturbance, anxiety, and depression (r’s 0.60 to 0.75). PROMIS-Fatigue SF scores showed dose-response relationships across fatigue severity descriptors and CDAI categories. CONCLUSIONS: These results provide robust evidence supporting the construct validity of the 4, 7, and 8-item PROMIS-Fatigue SFs. They capture fatigue across the spectrum of RA disease activity in diverse groups of individuals and should be considered for use as patient-centered assessments of disease control and treatment efficacy.