Sleep disturbance in osteoarthritis: linkages with pain, disability, and depressive symptoms.

OBJECTIVE: It is known that osteoarthritis (OA) increases the risk of sleep disturbance, and that both pain and sleep problems may trigger functional disability and depression. However, studies examining all 4 variables simultaneously are rare. The aim of this study was to examine cross-sectional and longitudinal associations of self-reported sleep disturbance with OA-related pain and disability and depressive symptoms.
METHODS: At baseline, 367 persons with physician-diagnosed knee OA reported sleep disturbances, pain, functional limitations, and depressive symptoms. At 1-year followup, all measures were repeated in 288 of the subjects. Baseline analyses examined the independent and interactive associations of sleep disturbance with pain, disability, and depression, net of demographics and general health. Longitudinal analyses used baseline sleep disturbance to predict the 1-year change in pain, disability, and depression.
RESULTS: At baseline, sleep was independently associated with pain and depression but not disability. The sleep-pain relationship was mediated by depressive symptoms; sleep interacted with pain to exacerbate depression among persons with high levels of pain. Baseline sleep disturbance predicted increased depression and disability, but not pain, at followup.
CONCLUSION: These data confirm known cross-sectional relationships between sleep disturbance and pain and depression and provide new insights regarding longitudinal associations among those variables. Depression appears to play a strong role in the sleep-pain linkage, particularly when pain is severe. The unique predictive role of sleep in the progression of disability requires further study but may be an important point of intervention to prevent OA-related functional decline among persons whose sleep is disrupted by OA-related pain.