Crohn's disease, fatigue, and infliximab: Is there a role for cytokines in the pathogenesis of fatigue?

Aim: To study the effect of infliximab on fatigue in relation to cytokine levels in Crohn's disease (CD) patients. Methods: Fourteen CD patients were blinded for treatment and received placebo at baseline, and infliximab 2 wk later, with a follow-up of 4 wk. Blood samples were drawn on a regular basis, and questionnaires on fatigue, depression, quality of life, and clinical disease activity were completed at regular intervals. Results: After placebo infusion, fatigue scores decreased within 3 d (3.5 points ± 1.1, P ≤ 0.01), but returned to baseline values 14 d after this infusion. The drop of fatigue scores following infliximab infusion sustained until the end of the study (3.8 points ± 1.4, P ≤ 0.05). Quality of life was increased at the end of the study compared to baseline values (138.6 ± 9.4 vs 179.4 ± 6.7; P ≤ 0.005), whereas depression scores were decreased (20.4 ± 9.4 vs 11.3 ± 2.2; P ≤ 0.01). No correlation between the severity of fatigue and the level of cytokines was observed. Conclusion: The reduction of fatigue after infliximab infusion is subjective to a placebo effect. The effect of infliximab on fatigue, however, persists while the placebo effect disappears after a short period of time. A clear role of cytokines could not be substantiated.