578 Independent relations of physical demands and psychosocial job resources with musculoskeletal complaints: a longitudinal study

Introduction Academic research has elaborated the impact of physical demands (PD) on musculoskeletal health for employees in physically demanding jobs. Studies investigating musculoskeletal complaints (MSC) are mainly cross-sectional, which is a limitation to draw conclusions on causality. In addition the role of psychosocial factors on the work floor for health is receiving more attention from different studies. This study was designed to examine longitudinally whether psychosocial job resources (job autonomy and social support) and physically demanding activities at work have independent effects on MSC 12 months later. Methods Results were based on a study including employees from a technology company in Belgium. For 457 persons full information (baseline and at one year follow-up) was available. The exposure measurements used in the study (PD and psychosocial job resources) were obtained from ‘the work design questionnaire’. A four-item scale concerning MSC in the previous six months was applied. Multiple linear regression analyses were conducted. Result Participants were between 22 and 67 years old (mean age was 48.8 years; SD 10.3). Men were highly represented (92.6% men) and 54.9% of the sample had a lower educational background. The independent relations of PD and psychosocial factors were tested in the final model after adjusting for gender, age, language, educational level and baseline MSC. Regression analyses indicated that PD were associated with greater MSC, 12 months later. Only work method autonomy had a negative effect on MSC. Social support, work decision autonomy and work scheduling autonomy had no significant effect. Discussion The first conclusion of the study was the confirmation of a positive relation between PD at work and MSC over time. The second conclusion was the independent negative effect of work method autonomy on MSC. The main strength of the study was its longitudinal design. A possible limitation was the underrepresentation of women.