Does the association between musculoskeletal pain and sickness absence due to musculoskeletal diagnoses depend on biomechanical working conditions?

To investigate single-site and multi-site musculoskeletal pain as predictors of future sickness absence due to musculoskeletal disorders (MSD) among blue-collar employees in food industry, and to study to what extent this relationship depends on physical loading at work. Survey responses of 901 employees on working conditions and musculoskeletal pain during the past week were linked to their future sickness absence records obtained from the personnel register of a food industry company. Negative binomial regression models were computed to determine associations of pain in one and in multi-site with the number of sickness absence days due to MSD during a four-year follow-up. Analyses were made in the whole cohort and stratified by the occurrence of repetitive movements and awkward postures (low/high). Multi-site pain occurred among 59 % in the total cohort and predicted sickness absence with a rate ratio of 1.48 [95 % confidence interval (CI) 1.21-1.80], adjusted for age, gender, biomechanical and psychosocial working conditions, body mass index and physical exercise. Similar associations were seen in the sub-cohorts with a low occurrence of repetitive movements (RR 2.18, CI 1.69-2.80) and awkward postures (RR 1.78, CI 1.39-2.28), but not in the sub-cohorts with a high occurrence of these exposure. Single-site pain was not predictive of sickness absence. A very high level of sickness absence in biomechanically strenuous work was found. Multi-site pain predicted sickness absence due to MSD among the employees with low exposure, but not among those with high exposure.