According to study, researchers examined Varicose veins are associated with increased risk of deep vein thrombosis, pulmonary embolism, and peripheral artery disease. The study has published in JAMA. The association was strongest for deep vein thrombosis (DVT), whereas the associations with PE and PAD may be affected by confounding factors, the researchers wrote.

Shyue-Luen Chang, MD, from the Vein Clinic, department of dermatology, Chang Gung Memorial Hospital and Chang Gung University College of Medicine in Taoyuan, Taiwan, and colleagues conducted a retrospective cohort study of participants aged at least 20 years without a history of DVT, PE or PAD in Taiwan’s National Health Insurance program between 2001 and 2013.

Chang and colleagues matched via propensity score 212,984 patients with varicose veins (mean age, 55 years; 69% women) with 212,984 controls without varicose veins (mean age, 54 years; 70% women) and compared incidence rates of DVT, PE and PAD.

Median follow-up was between 7 and 8 years for each group and outcome. Compared with controls, those with varicose veins had more incident DVT (6.55 per 1,000 person-years vs. 1.23 per 1,000 person-years; absolute risk difference, 5.32; 95% CI, 5.18-5.46) and significantly elevated risk for DVT (HR = 5.3; 95% CI, 5.05-5.56), according to the researchers.

Those with varicose veins had slightly higher incidence rates of and risk for PE (0.48 per 1,000 person-years vs. 0.28 per 1,000 person-years; absolute risk difference, 0.2; 95% CI, 0.16-0.24; HR = 1.73; 95% CI, 1.54-1.94) and PAD (10.73 per 1,000 person-years vs. 6.22 per 1,000 person-years; absolute risk difference, 4.51; 95% CI, 4.31-4.71; HR = 1.72; 95% CI, 1.68-1.77) compared with controls, Chang and colleagues wrote.

“Patients with varicose veins have increased incidence of inflammatory and prothrombotic markers,” the researchers wrote. “The inflammatory processes may cause the study outcomes of which the pathophysiology may be due to the inflammatory process.”

Many factors may contribute to confounding, including patients only seeking treatment for varicose veins when they become severe, potential confounders such as smoking and obesity not being included in the claims database, and the falsification endpoints of lung cancer and hyperlipidemia being associated with varicose veins.

“The magnitude of the association between varicose veins and PE and PAD was small, and, therefore, it may be more likely due to residual or unmeasured confounding,” Chang and colleagues wrote.