Sleep Disturbances in Korean Patients with Ankylosing Spondylitis are Associated with Increased Disease Activity

Abstract

Background/Purpose: Sleep problems have been reported to be more frequent in rheumatic disease than normal population. Other studies indicate various sleep problems have been reported in ankylosing spondylitis (AS). Inadequate sleep in AS patients is associated with multiple factors including pain, fatigue, disease activity and depression. In this study, we evaluated the prevalence of sleep disturbance in Korean patients with ankylosing spondylitis, and its association with disease activity and depression. Methods: Forty patients with AS and eighty healthy controls were included in the study. Participants completed questionnaires. Sleep quality was assessed using the Korean version of the Pittsburgh sleep quality index (PSQI). Depression was assessed by the Korean version of the Beck depression inventory second edition (BDI-2). The Bath ankylosing spondylitis disease activity index (BASDAI) and ankylosing spondylitis disease activity score-C-reactive protein (ASDAS-CRP) were used to evaluate disease activity. Patients were dichotomized into a good sleeper group (PSQI 5). Results: The mean total PSQI score of patients with AS was 7.23 +/- 3.84. It was higher than that of control subjects (p<0.001). AS patients had higher scores in the subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance and daytime dysfunction components. 60% of the AS patients classified as poor sleeper group. The mean ASDAS-CRP and BDI-2 score of poor sleeper group were higher than that of good sleeper group. Significantly, higher disease activity according to ASDAS-CRP was associated with poor sleep quality and depression. Stepwise multiple regression analysis revealed that duration of morning stiffness and depression were independent risk factors that influenced poor sleep quality. Conclusion: Sleep disturbances are prevalent amongst Korean patients with AS. Lower quality of sleep is significantly associated with higher disease activity and depression. Morning stiffness and depression were independent risk factors that influenced poor sleep quality. Therefore, evaluation and optimal management of morning stiffness and depression to improve sleep quality in patients with AS is important.