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

Abstract

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.

Keywords: Fatigue; PROMIS; Patient reported outcomes; Rheumatoid arthritis; Validation.

Conflict of interest statement

Ethics approval and consent to participate

This research was performed in accordance with the Declaration of Helsinki and was approved by review boards at Johns Hopkins (IRB00059765 and 0059930) with additional approval at University of Alabama at Birmingham (X150722003) and The Hospital for Special Surgery (2015–238). Written informed consent was obtained from all participants.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

Distribution of PROMIS Fatigue 7a, 8a, and 4a scores

Fig. 2

Bland-Altman plot showing correspondence between scores of PROMIS Fatigue short forms. Lines represent average difference and ± 1.96 standard deviation of the difference

Fig. 3

Box plots showing median and upper and lower interquartile ranges (IQR) of PROMIS Fatigue 4a, 7a, and 8a scores across Clinical Disease Activity Index levels and patient fatigue descriptors. Asterisks represent extreme scores > 1.5 IQR. REM = remission; LDA = low disease activity; MDA = moderate disease activity; HAD = high disease activity