Patterns of change of multisite pain over one year of follow-up and related risk factors

Abstract

Background: Multisite musculoskeletal pain is common and disabling. This study aimed to prospectively investigate distribution of musculoskeletal pain anatomically, and explore risk factors for increases/reductions in the number of painful sites. Methods: Using data from participants working in 45 occupational groups in 18 countries, we explored changes in reporting pain at 10 anatomical sites on two occasions 14 months apart. We used descriptive statistics to explore consistency over time in the number of painful sites, and their anatomical distribution. Baseline risk factors for increases/reductions by ≥3 painful sites were explored by random intercept logistic regression that adjusted for baseline number of painful sites. Results: Amongst 8,927 workers, only 20% reported no pain at either time point, and 16% reported ≥3 painful sites both times. After 14 months, the anatomical distribution of pain often changed but there was only an average increase of 0.17 painful sites. Some 14% workers reported a change in painful sites by ≥ 3. Risk factors for an increase of ≥ 3 painful sites included female sex, lower educational attainment, having a physically demanding job, and adverse beliefs about the work-relatedness of musculoskeletal pain. Also predictive were: older age, somatising tendency, and poorer mental health (each of which was also associated with lower odds of reductions of ≥ 3 painful sites). Conclusions: Longitudinally, the number of reported painful sites was relatively stable but the anatomical distribution varied considerably. These findings suggest an important role for central pain sensitisation mechanisms, rather than localised risk factors, among working adults.