Main and combined effects of musculoskeletal pain frequency and avoidant coping on sickness absence: findings from a prospective cohort study.

OBJECTIVE Musculoskeletal pain and avoidant coping predicts sickness absence, but how these 2 predictors relate to each other is unknown. We examined the main and combined effects of musculoskeletal pain and avoidant, behavioural coping on incidence of sickness absence. DESIGN AND SUBJECTS Prospective cohort study of a sample of middle-aged Danes, economically active in 2006, reporting functional limitations due to musculoskeletal pain, n = 3115. METHODS Data included surveys from 2000 and 2006 and register data from 2007. Outcome was sickness absence exceeding 2 consecutive weeks in 2007. The main effect of self-reported pain frequency and avoidant coping on sickness absence was analysed by multivariate logistic regression. The combined effect was calculated as departure from multiplicativity and by the inclusion of a product term. RESULTS Daily pain and use of avoidant coping were both associated with sickness absence in multiple adjusted analyses, odds ratio (OR)daily pain = 1.83 (95% confidence interval (CI) 1.51-2.21) and OR(avoidant coping) = 1.52 (95% CI 1.24-1.88) (main effects). A modest combined effect of musculoskeletal pain and avoidant coping on sickness absence was suggested (p = 0.286). CONCLUSION Avoidant coping and daily pain are both associated with sickness absence, but showed no strong signs of interactive effects. Clinicians should be aware of both factors.