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Thrombus
People with varicose veins may have an increased risk of venous thromboembolism (VTE) and peripheral artery disease (PAD), according to a new study.
The data suggested patients with varicose veins had a 5-fold higher risk of deep vein thrombosis (DVT) and roughly twice the risk of pulmonary embolism (PE) and PAD as patients without varicose veins.
Investigators said these results suggest an increased risk of DVT among patients with varicose veins, but “the findings for PE and PAD are less clear due to the potential for confounding.”
Pei-Chun Chen, PhD, of China Medical University in Taichung, Taiwan, and colleagues reported these findings in JAMA.
The team conducted this research using claims data in Taiwan’s National Health Insurance program. They assessed the risk of DVT, PE, and PAD in 212,984 patients with varicose veins and 212,984 control subjects. Patients and controls were matched by age, sex, and calendar year.
All study subjects were enrolled from 2001 to 2013 and followed through 2014.
Among the patients with varicose veins, the median duration of follow-up was 7.5 years for DVT, 7.8 years for PE, and 7.3 years for PAD. For controls, the median follow-up was 7.6 years for DVT, 7.7 years for PE, and 7.4 years for PAD.
Results
The incidence rate for DVT was 6.55 per 1000 person-years for patients with varicose veins (n=10,360) and 1.23 per 1000 person-years for controls (n=1980). The absolute risk difference (ARD) was 5.32.
The incidence rate for PE was 0.48 per 1000 person-years for patients with varicose veins (n=793) and 0.28 per 1000 person-years for controls (n=451). The ARD was 0.20.
The incidence rate for PAD was 10.73 per 1000 person-years for patients with varicose veins (n=16,615) and 6.22 for controls (n=9709). The ARD was 4.51.
The hazard ratios (for the varicose-veins group compared to controls) were 5.30 for DVT, 1.73 for PE, and 1.72 for PAD.
The investigators also calculated hazard ratios in a model adjusted for sex, age, index year, number of outpatient visits during the year before index date, and comorbidities. Comorbidities included hypertension, diabetes, chronic obstructive pulmonary disease, hyperlipidemia, malignancy, heart failure, ischemic heart disease, stroke, and chronic renal insufficiency.
In this adjusted model, the hazard ratios were 5.39 for DVT, 1.75 for PE, and 1.76 for PAD.
Limitations
The investigators said this study had several limitations.
First, the data did not include information for patients who didn’t seek medical care for varicose veins. Therefore, the results may reflect only the risk of VTE and PAD among patients with more severe varicose veins.
And the investigators were not able to examine whether the severity of varicose veins played a role in the risk of VTE or PAD.
In addition, information on some potential confounders, such as smoking and obesity, was not available. And the magnitude of the association between varicose veins and PE/PAD was small, so the association the investigators observed could be due to residual or unmeasured confounding.
The investigators also noted that diagnostic evaluations for PAD are more likely to occur in patients with varicose veins, which could partially explain the observed association between varicose veins and PAD.
Furthermore, cases of DVT, PE, and PAD could have been misclassified.