Functional Disability Mediates the Association Between Low Back Pain and Sleep Disturbance: Evidence from a Population-Based Study in Japan

Population-based cross-sectional study. To examine the associations of sleep disturbance with low back pain (LBP) and pain-related disability in a community-based setting in Japan. Sleep disturbance and LBP are highly prevalent and often overlap in ways that impair quality of life. Although their association has been reported, few population-based studies have simultaneously evaluated both LBP status and pain-related disability using validated assessment tools. Data from 2186 adults aged 20 to 90 years were analyzed. Sleep disturbance was assessed using the Athens Insomnia Scale (AIS; cutoff &#x2265;6), and its association with LBP and pain-related disability [measured by the modified Oswestry Disability Index (mODI)] was examined. Psychological distress was assessed using the Kessler Psychological Distress Scale (K6). Multivariable logistic regression analyses were conducted to identify factors independently associated with sleep disturbance. The Spearman rank correlation coefficients were calculated to examine the correlations between AIS scores and individual mODI items. The prevalence of LBP and sleep disturbance was 14.9% and 29.7%, respectively. Participants with sleep disturbance were more likely to report LBP and had significantly higher mODI and K6 scores. In regression models, chronic LBP was associated with sleep disturbance when mODI was not included; however, this association was no longer significant after inclusion of mODI, which itself remained robustly associated. Higher K6 scores were also independently related to sleep disturbance. Correlation analyses showed that among mODI items, "Pain intensity" ( r =0.329, P&#xa0; <&#xa0;0.001) and "Sitting" ( r =0.305, P&#xa0; <&#xa0;0.001) had the strongest correlations with AIS scores. Disability related to LBP, rather than pain itself, was significantly associated with sleep disturbance, and psychological distress was also independently associated with insomnia. Level II.