Data from participants enrolled in the secondary case-control study.

Years of age were expressed as mean±standard deviation. Age of cases: age at the first incident. Age of controls: age at enrollment. Age was further divided into three levels: under 40 years, 40 to 60 years, and over 60 years. Sedentariness/immobilization reflects the 4 weeks prior to the venous thrombosis incident. A Chi-squared test was used to compare the differences between groups according to gender, smoking status, alcohol abuse, malignant tumor, type 2 diabetes, sedentariness/immobilization, and pregnancy/puerperium. A Student's t test was used to compare the mean ages of the cases and controls. VT = venous thrombosis. T2DM = type 2 diabetes mellitus.