Venous thromboembolism risk associated with protracted work- and computer-related seated immobility: A case-control study.

OBJECTIVE: To examine the association between venous thromboembolism and prolonged work- and computer-related seated immobility.

DESIGN: A case-control study.

PARTICIPANTS AND SETTING: Cases were 200 patients attending venous thromboembolism clinics with a history of deep vein thrombosis and/or pulmonary embolism in the past six months, and controls were 200 patients treated in fracture clinic for an upper limb injury in the past six months.

MAIN OUTCOME MEASURES: Logistic regression was used to estimate the association between venous thromboembolism and prolonged work- and computer-related seated immobility in the 28 days before the index event. Prolonged work- and computer-related seated immobility was defined firstly as a categorical variable with at least 10 h seated in a 24-h period, including at least 2 h without getting up; and secondly as the actual time spent seated in a 24-h period.

RESULTS: Prolonged work- and computer-related seated immobility (categorical variable) was present in 36 (18%) cases and 31 (15.5%) controls. In multivariate analysis, there was no significant association between prolonged seated immobility and venous thromboembolism, odds ratio 1.18 (95% CI 0.56 to 2.48), P = 0.67. For the mean and maximum number of hours seated in a 24-h period, the odds ratios for the association per additional hour seated with venous thromboembolism were 1.08 (95% CI 1.01 to 1.6), P = 0.02 and 1.04 (95% CI 0.99 to 1.09), P = 0.08, respectively.

CONCLUSION: This study found a weak association between venous thromboembolism and prolonged work- and computer-related seated immobility, with increasing mean hours seated associated with a higher risk of venous thromboembolism.