Are changes in mechanical exposure and musculoskeletal health good performance indicators for primary interventions?

Objectives: The purpose of this review is to present more insight into the effects of primary interventions on both mechanical exposure and musculoskeletal health and to determine whether these outcomes are good performance indicators of such interventions. Methods: The literature was scrutinised for relevant references. Primary prevention was defined as any activity aimed at preventing the occurrence of musculoskeletal disorders in occupational populations. Primary outcome measures were mechanical exposure, musculoskeletal health, and sick leave due to musculoskeletal disorders. The impact of interventions was assessed by calculating the reduction in mechanical exposure and the preventable fraction (PF) of the musculoskeletal complaints. After selection, 40 studies were included for further analysis. Results: In general, of the 40 included studies, 29 (73%) found a reduction in musculoskeletal symptoms (PF range 0.10-0.95). Eighteen out of 29 studies (62%) reported a statistically significant reduction in musculoskeletal disorders. In 12 of the 40 studies (30%) changes in both mechanical exposure and musculoskeletal health were used as performance indicators for the intervention. Of these studies nine (67%) showed a reduction in both mechanical exposure (range 14%-87% reduction) and musculoskeletal disorders or sick leave due to musculoskeletal disorders (PF range 0.15-0.92). From these nine it was seen that a reduction of at least 14% in mechanical exposure resulted in a concomitant reduction in musculoskeletal health. Conclusions: More quantitative information is needed, to describe the relationship between mechanical exposure and musculoskeletal health as presented in the model: In this case it is recommended that in primary intervention studies not only changes in health outcomes be measured but also changes in mechanical exposure along the pathway of the intervention. In this way a better insight will be gained about the dose-response relationships between exposure to physical-load risk factors and work-related musculoskeletal disorders (WRMSD). More insight into these relationships will eventually lead to more efficient implementations of primary intervention strategies.