Longitudinal trajectories of fatigue in early RA: the role of inflammation, perceived disease impact and early treatment response.

Objective: Fatigue is common in rheumatoid arthritis (RA). We aimed to explore its longitudinal course, predictors and association with disease activity in early RA.

Methods: Data came from the 2-year treat-to-target trial CareRA (Care in early RA) and its 3-year extension. Fatigue was measured on Visual Analogue Scale, Multidimensional Fatigue Inventory and Short Form-36 (SF-36) vitality. Longitudinal fatigue trajectories were identified with multivariate growth mixture modelling. Early predictors of fatigue and the association of fatigue and its trajectories with disease activity and clinical/psychosocial outcomes were studied with linear mixed models and multilevel mediation.

Results: We included 356 and 244 patients in the 2-year and 5-year analyses, respectively. Four fatigue trajectories were identified: rapid, gradual, transient improvement and early deterioration, including 10%, 14%, 56% and 20% of patients. Worse pain, mental health and emotional functioning were seen in the early deterioration group. Higher pain, patient global assessment (PGA) and disability (Health Assessment Questionnaire), lower SF-36 mental components, and fewer swollen joints at baseline predicted higher fatigue over 5 years, while early disease remission strongly improved 5-year fatigue. The association between Simple Disease Activity Index and fatigue was mediated by PGA, pain, mental health and sleep quality.

Conclusions: Although fatigue evolves dynamically over time in early RA, most patients do not achieve sustained fatigue improvement despite intensive disease-modifying antirheumatic drug therapy. Higher 5-year fatigue levels were seen in patients with more perceived disease impact and fewer swollen joints at baseline. Conversely, early inflammatory disease control strongly improved long-term fatigue, pointing towards an early window of opportunity to prevent persistent fatigue.