Sedentary work and risk of venous thromboembolism

Objective Prolonged seated immobility during long-distance flights is related to an increased risk of venous thromboembolism (VTE), but little, if anything, is known about the risk related to sedentary work. The objective of this paper was to examine the risk of VTE according to sitting posture at work. Methods This prospective study includes a total of 78 936 participants from the Copenhagen City Heart Study and the Copenhagen General Population Study, all without previous thromboembolic events and aged <65 years. An assessment of the number of hours spent in sitting position at work was assigned each participant at baseline using a job exposure matrix. VTE was identified through national patient registries. Survival analyses were performed to determine the risk of VTE according to sedentary position at work with adjustment for a range of known determinants including lifestyle and coagulation factors. Results During the follow-up period of 582 411 person years (mean follow-up, 7.4 years) 911 participants experienced their first VTE event. Multivariable adjusted analyses showed no difference in risk of VTE between occupational sitting ≥6.5 hours/day and occupational sitting ≤3.5 hours/day (hazard ratio 1.11, 95% confidence interval 0.92-1.34). Conclusion This study does not support the hypothesis that sedentary work is a risk factor for VTE in the general population. Whether certain occupations with particularly high exposure to immobilized sitting positions are associated with thromboembolic events is not addressed.