Does sleep quality mediate the association of depressive symptoms with pain and disability in older adults with low back pain? A longitudinal population-based study

INTRODUCTION: Chronic low back pain (LBP) is common in older adults and can cause functional disability. It is often linked with depressive symptoms and poor sleep quality, which are factors related to each other that have bidirectional relationships with pain, forming a complex interdependent triad. OBJECTIVE: We examined whether sleep quality plays a mediating role in the association between depressive symptoms, pain, and disability in older adults with LBP. DESIGN: This study is an observational cohort. METHODS: A total of 171 participants aged ≥60 years were interviewed. Data on depressive symptoms (Center for Epidemiologic Studies Depression Scale), sleep quality (Pittsburgh Sleep Quality Index), pain intensity (Numeric Pain Scale), and functional disability (Roland-Morris Disability Questionnaire) were collected at different time-points (baseline, 6 months, and 12 months). Mediation analysis was used to assess whether sleep quality was a mediating factor in the relationship between pain and depressive symptoms. RESULTS: The results indicated that sleep quality at 6 months significantly mediated the association between baseline depressive symptoms with both pain intensity and functional disability at 12 months. The influence of baseline insomnia symptoms on outcomes at 12 months depended on sleep quality at 6 months. The indirect mediation explained 43.4% of the relationship with pain intensity and 47.9% with functional disability. CONCLUSION: Sleep quality was found to mediate the relationship between depressive symptoms and pain/disability. These findings highlight the importance of assessing/improving sleep quality in older adults with LBP and depressive symptoms.