Are varicose veins associated with increased risk of blood clot?

Bottom Line: Varicose veins were associated with increased risk of developing a type of blood clot known as a deep venous thrombosis (DVT), although more research is needed to understand the strength of that association.

Why The Research Is Interesting: Varicose veins are common, with about 23 percent of U.S. adults having the condition, but they are rarely associated with serious health risks. Not much is known about varicose veins and the risk of other vascular diseases including DVT, pulmonary embolism (PE) and peripheral artery disease (PAD).

Who and When: 212,984 patients with varicose veins and 212,984 without varicose veins from claims data in Taiwan's National Health Insurance program; patients were enrolled from 2001 to 2013 and followed up through 2014

What (Study Measures): Varicose veins (exposure); risk of developing DVT, PE and PAD in people with and without varicose veins (outcomes)

How (Study Design): This was an observational study. Researchers were not intervening for purposes of the study and cannot control all the natural differences that could explain study findings.

Authors: Pei-Chun Chen, Ph.D., China Medical University, Taichung, Taiwan, and coauthors

Results: Varicose veins were associated with increased risk of DVT but more research is needed to understand whether that association is causal or if it reflects a common set of risk factors. Findings about potential associations between varicose veins and risk of PE and PAD were less clear because of possible confounding factors.

Study Limitations: Claims data do not include information for patients who do not seek medical care; study results may reflect only the risk among patients with more severe varicose veins requiring medical treatment.

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For more details and to read the full study, please visit the For The Media website.

(doi:10.1001/jama.2018.0246)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.