Multisite musculoskeletal pain trajectories from midlife to old age: a 28-year follow-up of municipal employees

Objectives We studied the developmental trajectories of multisite musculoskeletal pain (MSP) to learn whether pain in midlife persists to old age, and whether pain trajectories associate with midlife work or lifestyle exposures or retirement from work. Methods Municipal employees aged 44-58 years were studied in 1981 (n=6257) with follow-ups in 1985, 1992, 1997 and 2009. Pain in the neck, low back, and upper and lower limbs was assessed in each survey. Trajectories of the number (0-4) of pain sites were defined using growth mixture modelling (n=3093). Workload, lifestyle and morbidity were elicited by questionnaire and retirement from registries. Associations of baseline factors with pain trajectories were assessed by multinomial logistic regression. Cumulative hazard curves for retirement by trajectory group were calculated. Results T hree trajectories of pain over 28 years emerged: low (25%), moderate (52%) and highdecreasing (23%). In the latter, the number of pain sites first decreased sharply, stabilising to a moderate level after most subjects had retired. The disability pension rate was highest in this trajectory, which associated with high baseline morbidity, particularly musculoskeletal disorder (OR 8.06; 95% CI 5.97 to 10.87). Also high biomechanical exposure (2.86; 95% CI 2.16 to 3.78), high job demands (1.79; 95% CI 1.39 to 2.30), high job control (OR 0.70; 95% CI 0.54 to 0.90), body mass index (BMI) >= 25.0 kg/m(2) (1.40; 95% CI 1.09 to 1.80) and low leisure-time physical activity (LT PA) (1.39; 95% CI 1.09 to 1.78) at baseline were associated with this trajectory. However, high LT PA and BMI in repeated surveys also associated with the high-decreasing trajectory. Conclusion MSP in midlife often persists to old age. However, high widespreadness of pain may decrease with retirement from work.