Interleukin 6 (IL-6)-mediated interactions have been associated with sleep disturbances in healthy subjects. In this pilot study we examined whether administration of the IL-6 receptor antagonist tocilizumab in patients with rheumatoid arthritis (RA) affects sleep disturbances.
Fifteen patients (13 women) with sleep disturbances at baseline received 6 monthly infusions of tocilizumab 8 mg/kg for moderately or severely active RA. Sleep quality was assessed by Pittsburgh Sleep Quality Index (PSQI), daytime sleepiness by Epworth Sleepiness Scale, disease activity by the 28-joint Disease Activity Score-erythrocyte sedimentation rate, functional disability by Health Assessment Questionnaire Disability Index (HAQ-DI), and fatigue by the Functional Assessment of Chronic Illness Therapy (FACIT-Fatigue Scale; FFS) at baseline and first, second, third, and sixth month of treatment. Medications used before enrollment remained unchanged during followup.
Sleep quality improved and daytime sleepiness decreased significantly at first-month assessment (p < 0.00001 and p < 0.004, respectively, by repeated measurement analysis) compared to baseline, and these changes became more evident through 6 months. Disease activity decreased, fatigue decreased, and functional status improved significantly. Changes in PSQI score over time were not associated with the corresponding changes in DAS28-ESR (r = 0.37, p = 0.17), but correlated significantly with HAQ-DI changes (r = 0.60, p = 0.02) and marginally with changes in FFS scores (r = -0.46, p = 0.08).
Improvement of sleep quality after tocilizumab treatment in patients with RA does not appear to directly result from decreased disease activity, further suggesting that aberrant IL-6 regulation is associated with sleep disturbances.