The potential role of fatigue in difficult-to-treat rheumatoid arthritis.

Objectives: A subset of patients with rheumatoid arthritis (RA) who remains symptomatic after failing to multiple drugs are deemed to have "difficult-to-treat RA" (D2T RA). Fatigue is a burdensome symptom for RA patients, hindering their improvement. Our purpose was to evaluate the role of fatigue in D2T RA.

Methods: This cross-sectional study included rheumatoid arthritis (RA) patients between 2018 and 2022, treated with biological agents or targeted synthetic disease-modifying antirheumatic drugs. D2T RA was defined attending EULAR criteria. Independent variable was fatigue (dimensions and impact) assessed by the Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire and Numerical Rating Scales. Covariables: sociodemographic, clinical and treatment. To identify factors independently associated to D2T RA, multivariable logistic regression was run.

Results: The study included 145 patients and 38 (26.21%) developed D2T RA. D2T RA group were older, with more comorbidity and disability. D2T RA patients scored higher for global fatigue (p = 0.003), and almost for all their dimensions except for cognitive fatigue (p = 0.06) and fatigue coping (p = 0.07). Females with D2T RA showed more fatigue than those with non-D2T RA. In the adjusted models, all fatigue dimensions were associated with D2T RA: global fatigue RA (OR: 1.03; p = 0.007), physical (OR: 1.09; p = 0.008), living (OR: 1.09; p = 0.016), cognitive (OR: 1.1; p = 0.046) and emotional (OR: 1.18; p = 0.012).

Conclusions: Despite the absence of an explicit mention of fatigue in the definition of D2T RA, it appears to be associated to this outcome. Fatigue should be evaluated in a multidimensional perspective, and gender-specific differences should be considered.