Impact of musculoskeletal pain on insomnia onset: a prospective cohort study.

OBJECTIVE: Pain, the most common manifestation of rheumatological conditions, is highly prevalent among older adults, with worse health outcomes found in those with co-morbid insomnia. Proactive prevention of insomnia may reduce the overall disease burden of pain and rheumatological conditions. To inform such development, this study examined the role of pain, physical limitation and reduced social participation in predicting and mediating insomnia onset. METHODS: A prospective cohort study was conducted involving 6676 individuals ≥50 years of age who completed questionnaires at baseline and a 3-year follow-up. Participants were classified into none, some and widespread pain according to the ACR criteria. Logistic regression was used to examine the relationship between baseline pain and insomnia onset at 3 years. Path analysis was used to test for the mediating role of physical limitation and social participation restriction. RESULTS: Some [adjusted odds ratio (AOR) 1.57 (95% CI 1.15, 2.13)] and widespread [2.13 (1.66, 3.20)] pain increased the risk of insomnia onset at 3 years, after adjusting for age, gender, socio-economic class, education, anxiety, depression, sleep and co-morbidity at baseline. The combination of physical limitation and reduced social participation explained up to 68% of the effect of some pain on insomnia onset and 66% of the effect of widespread pain on insomnia onset. CONCLUSION: There was a dose-response association between the extent of pain at baseline and insomnia onset at 3 years that was substantially mediated by physical limitation and reduced social participation. Targeting physical limitation and social participation in older people with pain may buffer co-morbid insomnia, reducing the overall disease burden.