The bidirectional relationship between headache and chronic musculoskeletal complaints: an 11-year follow-up in the Nord-Trøndelag Health Study (HUNT).

Background and purpose Chronic daily headache (CDH) and chronic musculoskeletal complaints (CMSCs) are associated disorders, but whether there is a causal relationship between them is unclear. Objective To determine whether CMSCs are associated with the subsequent development of CDH and vice versa. Methods This longitudinal population-based cohort study used data from two consecutive surveys in the Nord-Trondelag Health Study (HUNT 2 and 3) performed in 19951997 and 20062008. Amongst the 51383 participants aged=20years at baseline, 41766 were eligible approximately 11years later. Of these, 26197 (63%) completed the questions regarding headache and CMSCs in HUNT 3. Results A bidirectional relationship was found between headache and CMSCs. In the multivariate analyses adjusting for known potential confounders, a nearly two fold risk (OR 1.8; 95% CI 1.52.3) for developing CDH was found for those with CMSCs at baseline. Vice versa, a similarly elevated risk of CMSCs (OR 1.8; 95% CI 1.22.6), and even higher risk of chronic widespread MSCs (OR 2.7; 95% CI 1.64.7), was found at follow-up amongst those with CDH at baseline. Conclusion CMSCs predispose to CDH and CDH predisposes to CMSCs 11years later. This may have relevance to understanding the pathophysiology of these disorders. CMSCs should be treated not only to relieve them but also to prevent the development of CDH, and vice versa.