Impact of sleep quality on clinical features of primary Sjögren's syndrome

BACKGROUND/AIMS: This study aimed to investigate the inf luence of poor sleep quality on clinical features of primary Sjögren’s syndrome (pSS). METHODS: Sleep quality was cross-sectionally assessed using the Pittsburgh Sleep Quality Index (PSQI), and demographic, clinical, and laboratory data were collected from 115 Korean patients with pSS. The patients completed questionnaires on the European League Against Rheumatism (EULAR) SS Patient Reported Index (ESSPRI), quality of life (EuroQOL five dimensions questionnaire [EQ-5D]), fatigue (fatigue severity score [FSS]), and depression (Beck Depression Inventory [BDI] II]). Symptoms and patient global assessment (PGA) were evaluated with a 100-mm visual analogue scale (VAS). The EULAR sicca score (ESS), ESSPRI, and EULAR SS Disease Activity Index (ESSDAI) were calculated at study enrollment. RESULTS: Fifty-three patients (46.1%) had poor sleep quality and 32.4% of 71 patients without depression were poor sleepers. Poor sleepers had a significantly lower EQ-5D or ESSDAI and a significantly higher FSS, BDI-II, PGA, ESS, ESSPRI, or VAS scores for extra-glandular symptoms than good sleepers. Neutrophil and lymphocyte counts were significantly higher and immunoglobulin G levels tended to decrease in poor sleepers. Additionally, PSQI was negatively correlated with EQ-5D and ESSDAI and positively with ESS, FSS, BDI-II, PGA, VAS scores for their symptoms, and ESSPRI. Multivariate analysis revealed that poor sleep quality remained the independent determinants of the unsatisfactory symptom state (ESSPRI ≥ 5). CONCLUSIONS: Our results showed that poor sleep quality could significantly affect the patient-oriented outcomes and physician-reported activity index of pSS patients through the various effects of sleep quality on the psychological or somatic symptoms and the immune system.