Fatigue independently predicts different work disability dimensions in etanercept-treated RA and AS patients

Katie Druce, Laraine Aikman, Maria Dilleen, Annie Burden, Piotr Szczypa, Neil Basu

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21 Citations (Scopus)
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Background: Work disability remains a significant problem in ankylosing spondylitis (AS) and rheumatoid arthritis (RA), despite biological therapy. This study aimed to test the hypothesis that the prevalent symptom of fatigue longitudinally predicts work disability among RA and AS patients commencing etanercept.

Methods: Two observational studies, comprising RA and AS etanercept commencers respectively, were analysed. Both provided data on work disability over 1 year and a comprehensive set of putative predictors, including fatigue. A series of repeated measures models were conducted, including baseline variables, visit (6/12 months) and the interaction between visit and each of the explanatory variables.

Results: A total of 1003 AS, and 1747 RA, patients were assessed. For AS, fatigue was significantly associated with presenteeism (linear mixed model coefficient: 3.75, 95% CI 2.14 to 5.36) and activity impairment (2.62, 1.26 to 3.98), but not with work productivity loss (1.81, -0.40 to 4.02) or absenteeism (generalised linear mixed model OR: 1.18, 95% CI 0.92 to 1.51). In RA, fatigue was associated with presenteeism (coefficient: 3.44, 95% CI 2.17 to 4.70), activity impairment (1.52, 0.79 to 2.26), work productivity loss (4.16, 2.47 to 5.85) and absenteeism (OR: 1.23, 95% CI 1.02 to 1.49). The lack of significant interactions between fatigue and visit supported a consistent effect of baseline fatigue over time.

Conclusions: Among patients beginning etanercept therapy, fatigue has a significant and independent effect on the absenteeism, presenteeism, productivity loss and activity impairment of RA patients and a significant but dimension selective effect on work disability among AS patients.

ClinicalTrials.gov Trial Registration: NCT00544557: 16/10/2007, NCT00488475: 20/06/2006
Original languageEnglish
Article number96
JournalArthritis Research & Therapy
Publication statusPublished - 29 May 2018

Bibliographical note

Funding: This study was supported by Pfizer. The sponsor was involved in the study design, collection, analysis and interpretation of data as well as revising the manuscript for intellectual content.


  • fatigue
  • work disability
  • rheumatoid arthritis
  • spondyloarthritis


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