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
³Venenpraxis, Wunstdorf, Germany

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Introduction: Every fifth worker in the EU is spending most of the working time in standing posture. According to pathophysiological mechanisms, prolonged standing contributes to developing varicose veins (VV). Previous studies investigating the effect of prolonged standing at work on VV used subjective and retrospective measures to assess standing exposure. Advances in technology now enable to objectively measure standing time at work. The aim of this cross-sectional field study was to explore the association between standing time at work and VV among employees, measured by accelerometer.

Methods: Cumulative standing time during a representative workday was tracked using accelerometers (ActiGraph GT9X Link, ActiGraph, US). Additionally, participants underwent CEAP classification assessments of lower extremities. VV is defined as ≥C2 (C ranges from C0 to C6, increasing with severity). To analyse the impact of occupational standing time on VV, participants were divided into three groups based on their cumulative standing time per workday: ≤2 vs. >2 but ≤4 vs. >4 h. Further, cumulative sitting and walking times were extracted from accelerometer data for a detailed description of the work postures. The association between cumulative standing time and other potential predictor variables on VV-presence (0=no; 1=yes) was analysed by multivariate binary logistic regression with a forward-backward approach.

Results: 198 employees working at least 30h and four days per week for at least two years in logistics, trade, retail, manufacturing, healthcare, research, and service sectors were included (116♀, Ø-age=40±9 y). Of these, 24% (n=47) were described with VV. Out of all, 18% (n=36) stood ≤2 h, 46% (n=91) >2 but ≤4 h, and 36% (n=71) >4 h per day. Those standing ≤2 h sat for an average of 340±126 min of the working day, while those standing >2 but ≤4 h sat 160±77 min, and those standing >4 h sat 90±69 min. Those standing ≤2 h walked 73±47 min during the workday, while those standing >2 but ≤4 h walked 129±54 min, and >4 h walked 120±43 min. In the final multivariate models, the cumulative standing time during a workday was not statistically significantly associated with VV-presence. Higher age and family history of VV were statistically significantly associated with VV.

Discussion: Contrary to previous studies, standing was not significantly associated with VV in the multivariate model. Among employees over 40 years of age, those standing ≤2 h per day had a higher prevalence of VV than those standing >4 h per day. This may indicate a healthy worker survivor effect among those with higher exposure, suggesting that standing-related VV risks may be underestimated. Pathophysiological mechanisms suggest that only walking reduces static pressure in veins indicating that the amount of walking is an important factor in the prevention of work-related VV. While standing and sitting times differed across the three analysed groups, walking time showed less variation.

Conclusion: Our data mostly covered subjects exposed to prolonged sitting and/or standing. We are currently conducting a follow-up study in a more heterogenic sample in terms of occupational walking time during a workday, to be able to consider the potential protective effect of walking on VV development.