Association of Varicose Veins With Incident Venous Thromboembolism and Peripheral Artery Disease.

Importance: Varicose veins are common but rarely associated with serious health risks. Deep venous thrombosis (DVT), pulmonary embolism (PE), and peripheral artery disease (PAD) are also vascular diseases but associated with serious systemic effects. Little is known about the association between varicose veins and the incidence of other vascular diseases including DVT, PE, and PAD. Objective: To investigate whether varicose veins are associated with an increased risk of DVT, PE, or PAD. Design, Setting, and Participants: A retrospective cohort study using claims data from Taiwan's National Health Insurance program. Patients aged 20 years and older with varicose veins were enrolled from January 1, 2001-December 31, 2013, and a control group of patients without varicose veins were matched by propensity score. Patients previously diagnosed with DVT, PE, or PAD were excluded. Follow-up ended December 31, 2014. Exposures: Presence of varicose veins. Main Outcomes and Measures: Incidence rates of DVT, PE, and PAD were assessed in people with and without varicose veins. Cox proportional hazards models were used to estimate relative hazards, with the control group as reference. Results: There were 212 984 patients in the varicose veins group (mean [SD] age, 54.5 [16.0] years; 69.3% women) and 212 984 in the control group (mean [SD] age, 54.3 [15.6] years; 70.3% women). The median follow-up duration was 7.5 years for DVT, 7.8 years for PE, and 7.3 years for PAD for patients with varicose veins, and for the control group, follow-up duration was 7.6 years for DVT, 7.7 years for PE, and 7.4 years for PAD. The varicose veins group had higher incidence rates than the control group for DVT (6.55 vs 1.23 per 1000 person-years [10 360 vs 1980 cases]; absolute risk difference [ARD], 5.32 [95% CI, 5.18-5.46]), for PE (0.48 for the varicose veins group vs 0.28 for the control group per 1000 person-years [793 vs 451 cases]; ARD, 0.20 [95% CI, 0.16-0.24]), and for PAD (10.73 for the varicose veins group vs 6.22 for the control group per 1000 person-years [16 615 vs 9709 cases]; ARD, 4.51 [95% CI, 4.31-4.71]). The hazard ratios for the varicose veins group compared with the control group were 5.30 (95% CI, 5.05-5.56) for DVT, 1.73 (95% CI, 1.54-1.94) for PE, and 1.72 (95% CI, 1.68-1.77) for PAD. Conclusions and Relevance: Among adults diagnosed with varicose veins, there was a significantly increased risk of incident DVT; the findings for PE and PAD are less clear due to the potential for confounding. Whether the association between varicose veins and DVT is causal or represents a common set of risk factors requires further research.