¹Institute of Occupational and Social Medicine and Health Services Research, University Hospital of Tübingen, Tübingen, Germany
²Institute of Sports and Sports Science, Karlsruhe Institute of Technology, Karlsruhe, Germany

Text

Introduction: Standing work is associated with health risks and current risk assessment approaches are mainly based on expert opinions. We aimed to develop and validate a new risk assessment approach for standing workplaces on the basis of surrogate parameters for venous disorders and musculoskeletal complaints.

Methods: Data from four laboratory studies (total of 134 participants) were used to model the influence of standing, sitting, walking, and alternation patterns of standing and walking on lower leg edema (surrogate for stress on the veins) and musculoskeletal discomfort in the lower back and limbs (surrogate for stress on the musculoskeletal system). All studies used the same methodology to measure lower leg edema (bioelectrical impedance and waterplethysmography) and musculoskeletal discomfort (11-point musculoskeletal discomfort scale). We used a multi-dimensional nonlinear regression approach including the variables exposure duration, the number of steps per minute, proportion of time spent sitting, and cycle time for data modelling. Cut-off values for risk categorization were derived from the scientific literature and resulted in four categories (low, moderate, substantial, high).

In addition, we conducted a cross-sectional field study to validate the association between our risk assessment approach and the prevalence of venous and musculoskeletal disorders. Standing, walking and sitting behaviors of 198 employees from different professions were collected during one representative workday using a wearable sensor at the thigh (ActiGraph, GT9X). These data served as input to describe the health risks of each participant at the given workplace. We aimed to balance the subjects /workplaces according to the four risk categories. Each participant underwent venous and musculoskeletal status evaluation by the CEAP classification of venous disorders and the Cornell Musculoskeletal Discomfort Questionnaire, respectively. Multiple logistic regression analyses were used to analyze the association of risk levels (four levels) and health outcomes (frequency of venous disorders and musculoskeletal disorders).

Results: Three risk predictions models (venous disorders, musculoskeletal complaints in the lower back, and limbs) were created and used as basis for risk categorization together with the ActiGraph data. Most of the participants from the cross-sectional study were rated having a high or substantial risk. After adjusting for age our logistic regression found no significant association between risk assessment level and venous or musculoskeletal health impairments.

Discussion: The predictive models based on surrogate parameters assessed during laboratory studies enable to predict health risks at standing workplaces. The cross-sectional validation failed to identify associations between our risk assessment and health-outcomes. The unwanted dominance of workplaces associated with high risks but also the quality of exposure assessment (only one working day) may have affected our results.

Conclusion: Post-recruitment has been initiated to include another 50 subjects focusing on more active workplaces to exploratively analysis the potential association of our risk assessment and health outcomes.