Preliminary study of the association of serum irisin levels with poor sleep quality in rheumatoid arthritis patients

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 score≤5 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 = -0.722 to -0.263 & p values≤0.001-0.04) 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.

Evaluation of cognitive function in systemic sclerosis patients: a pilot study

OBJECTIVE

To investigate cognitive dysfunction in adult patients with systemic sclerosis (SSc) who had no known clinical neurological manifestations and to relate it with other disease severity parameters.

METHODS

In the present study, 20 SSc consecutive female patients, who met the 2013 American College of Rheumatology SSc criteria, were compared with 20 healthy age-, gender-, and educational status-matched volunteer hospital workers. Mean age and duration of illness were 41.8 ± 12.52 and 6.9 ± 5.4 years respectively. Mini-Mental State Examination (MMSE), Wechsler Adult Intelligence scale (WAIS-III), and P300 component of event-related potentials (ERPs) were used to evaluate cognitive function in SS subjectively and objectively respectively.

RESULTS

Sixty-five percent (13 out of 20) of SSc patients had MMSE score < 25, and cognitive impairment. Despite the lack of clinically apparent neurological manifestations, SSc patients had significantly low MMSE score, high Deterioration Index (DI), and prolonged P300 latency compared with that of the control group (P = 0.0001; 0.010 and 0.008 respectively). A significant positive association was found between (DI) and the Medsger severity vascular score (r = 0.518; P = 0.012).There were few differences between limited and diffuse SSc.

CONCLUSIONS

To our knowledge, few studies highlighted that subclinical cognitive impairment can occur in the course of SSc disease. Early diagnosis of cognitive impairment should be investigated either subjectively (using psychometrics tests as MMSE or WAIS-III) or objectively using P300 evoked related potentials. Medsger severity vascular score seems to be closely related to cognitive impairment.Key points• Cognitive impairment can be associated with Medsger Vascular severity score and the duration of illness.• Further larger studies will be needed to estimate the effect of disease activity on cognitive function, to further delineate the differences between limited and diffuse SSc in this area, and to understand the underlying pathophysiological mechanisms causing cognitive impairment in patients with SSc.• To investigate impaired cognitive function in patients with SSc, even in the absence of clinically apparent neurological and vascular disease.