Study objectives: Sleep disorders are significant problems in patients with rheumatoid arthritis (RA) and
are associated with poor quality of life. Irisin is myokine which may have anti-inflammatory and energy
regulatory roles. This study assessed the association of serum irisin levels with the quality of sleep and
disease activity in RA patients.
Methods: In sum, 58 RA patients and 30 matched healthy controls were included. Disease activity score
in 28 joints (DAS28-ESR) and the patients’ global score were calculated. RA patients were grouped according
to the Pittsburgh Sleep Quality Index score (PSQI) into good-sleepers (group 1) defined as a PQSI
score5 and poor sleepers (group 2) with a PSQI > 5. Serum irisin levels were measured for both patients
and controls by commercially available enzyme-linked immunosorbent assay kits.
Results: Poor sleep quality was found in 26 (45%) of the RA patients. Irisin levels were significantly lower
in RA patients with poor sleep compared to those with good sleep and healthy controls (p < 0.001).
Serum irisin levels correlated inversely with disease duration, morning stiffness duration, DAS28-ESR,
global score, and total PSQI score (r ¼ 0.722 to 0.263 & p values0.001e0.04) indicating a possible
anti-inflammatory role of irisin in RA patients. The analysis employed Student's t-test, ANOVA, and
Pearson correlation.
Conclusions: Irisin levels were decreased in RA patients with poor sleep quality compared to RA patients
with good sleep quality and healthy controls, indicating a possible association of decreased serum irisin
with sleep impairment in RA patients.