Superficial Vein Thromboses Put People at Risk for Subsequent Blood Clots

Until recently, a superficial vein thrombosis (SVT) was seen as a painful induration of limited clinical significance. New evidence from a large population-based study published in Blood advises health care providers to not neglect the prognostic importance of SVTs.

European researchers, led by Suzanne Cannegieter, MD, of Leiden University Medical Centre in The Netherlands, determined that patients presenting with SVTs have both higher short- and long-term risk for venous and arterial thrombotic events.

The results reinforcce the importance of following guidelines on anticoagulant management of SVTs, Dr. Cannegieter told ASH Clinical News. The research team reviewed the medical records of 10,973 patients with a first-time diagnosis of SVT over a 32-year period (1980–2012) in the Danish National Registry of Patients. They compared this group with medical records from more than 515,000 age- and gender-matched subjects from the general Danish population.

Outcomes included venous thromboembolism, acute myocardial infarction (AMI), ischemic stroke, and death. In analyses, the researchers accounted for factors related to occurrence of SVT – such as cancer, surgery, pregnancy, autoimmune disease, and fracture – that could also affect the outcome of interest.

In the SVT cohort, 1,170 people developed deep-vein thromboses (DVT) over a median follow-up of 6.4 years, for an incidence rate of 12.8 per 1,000 patient-years (95% CI 12.1-13.6). In the comparison cohort, 6,096 people developed DVT over a median follow-up of 8.4 years, for an incidence rate of 1.2 per 1,000 patient-years (95% CI 1.1-1.2).

The age- and gender-adjusted hazard ratio (HR) for developing DVT was 11.8 (95% CI 11.1-12.6). Notably, this risk was highest in the first three months post-SVT (3.4%; 95% CI 3.0-3.7). Compared with the general population, the HR for SVT patients was 71.4 (95% CI 60.2-84.7) within this period, decreasing steadily – but remaining high – five years after SVT (HR=5.1; 95% CI 4.6-5.5).

SVT patients also faced an increased risk of pulmonary embolism (PE), with an incidence rate of 4.5 per 1,000 patient years (95% CI 4.1-4.9) in the SVT cohort, compared with 0.9 (95% CI 0.9-1.0) in the general population.

“There is a substantial short-term risk of DVT or PE in the first months after an SVT,” Dr. Cannegieter told ASH Clinical News. “Most guidelines now advise anticoagulant treatment of the SVT, in order to prevent more serious events. This high risk and its implications for treatment are something clinicians should be aware of.”

As evidenced by the high five-year risk, “the risk remains increased in the long-run as well, meaning that a patient with a history of SVT should be carefully advised during high-risk situations for DVT/PE (e.g. surgery, plaster cast),” she explained. “Anticoagulant prophylaxis should be strictly adhered to in these situations.”

SVT patients also faced a higher risk of acute myocardial infarction (AMI) than the general population: 5.8 versus 4.8 per 1,000 patient-years. In addition, SVT patients had a higher risk for ischemic stroke and mortality – again, with the greatest risk closest to the time of SVT.

When the results were stratified by gender, men had a greater relative risk for thromboembolic outcomes – despite the fact that women comprised about 60 percent of SVT patients (TABLE). Dr. Cannegieter attributed this risk to the fact that men have a higher pro-thrombotic tendency, contributing to the higher risk for DVT development once an SVT is present.

In the future, Dr. Cannegieter and her research group plan to mine medical records for further information on the extent or site of the SVT and treatment options. “The effect of anticoagulant treatment in daily practice has only been studied in small, randomized control trials, so far,” she said, citing the need for more data about newer target-specific oral anticoagulants and the optimal duration of treatment.

“We also need a better understanding of the etiology of SVT, as its risk factors are not exactly the same as for DVT or PE,” Dr. Cannegieter added. “If we know more about its causes, some more options on prevention may also become available.”


Reference

    Cannegieter SC, Horvath-Puho E, Schmidt M, et al. Risk of venous and arterial thrombotic events in patients diagnosed with superficial vein thrombosis: a nationwide cohort study. Blood. 2015;125(2):229-35.
TABLE. Adjusted Hazard Ratios for Venous Events, Stratified by Gender
Men (95% CI) Women (95% CI)
VTE 11.28 (10.37-12.27) 6.92 (6.40-7.48)
Unprovoked VTE 13.19 (11.93-14.57) 8.05 (7.33-8.84)
Provoked VTE 7.90 (6.75-9.25) 5.07 (4.38-5.87)
DVT 14.34 (12.98-15.85) 9.26 (8.41-10.19)
PE 5.81 (4.97-6.80) 3.83 (3.34-4.40)
AMI 1.25 (1.11-1.40) 1.09 (0.96-1.24)
Ischemic stroke 1.36 (1.21-1.53) 1.22 (1.10-1.35)
Death 1.34 (1.28-1.41) 1.22 (1.18-1.27)

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