Early changes in fatigue and cytokine concentration following etanercept treatment in rheumatoid arthritis

Aim: To study early changes in fatigue, disease activity and cytokines within individual patients with rheumatoid arthritis (RA) following etanercept treatment. Methods: 12-week prospective observational study of 21 RA patients starting etanercept therapy. DAS28, fatigue, IL-1β, IL-4, IL-6, IL-8 and IL-1ra were measured. Results: DAS28, fatigue and IL-6 improved significantly by 40% compared with baseline values in the first 4 weeks (P < 0.05), but followed different time courses. The main improvement in IL-6 occurred by week 2, fatigue (BRAF MDQ) by week 3 and DAS28 by week 4. At week 3 improvement of DAS28 (24%) was significantly less than BRAF MDQ (42%, P < 0.003) and IL-6 (43%, P < 0.03). Conclusion: Fatigue improved faster than disease activity, suggesting that fatigue may be mediated via a different pathway.