Sleep Quality Independently Affects Health-related Quality of Life and Cognitive Function in Korean Female Patients with Rheumatoid Arthritis: a Case-control Study

BACKGROUND: This study aimed to address sleep quality in patients with rheumatoid arthritis (RA) and to determine how it affects health-related quality of life (HRQoL) and cognitive function. METHODS: One hundred and twenty-three patients with RA and 76 healthy controls were enrolled in this study. Sleep quality was assessed using the Korean version of the Pittsburgh Sleep Quality Index (PSQI). Cognitive function and HRQoL was evaluated by a Korean-Montreal Cognitive Assessment (MoCA-K) and 36-item Short-Form Health Survey (SF-36), respectively. Other clinical, demographic, and laboratory data were obtained from retrospective medical chart review. RESULTS: More patients in the RA group reported poor sleep quality (PSQI > 5) than in the control group (61% [75/123] vs. 39.5% [30/76]; P = 0.003). Total PSQI was also significantly higher in the RA group (median [interquartile range], 7 [5–11] vs. 5 [3–6.75]; P = 0.001). Total PSQI score negatively correlated with MoCA-K score (Spearman's rho (r) = −0.223; P = 0.003) with a physical component summary (PCS) of SF-36 (r = −0.221; P = 0.003) and a mental component summary (MCS) of SF-36 (r = −0.341; P < 0.001), which means that poor sleep quality was associated with poor cognitive function and low HRQoL. CONCLUSION: The findings of this study suggest that poor sleep quality is an independent risk factor for low HRQoL and cognitive dysfunction. Efforts to improve the sleep quality of RA patients seem to be an important aspect of integrative treatment for RA.