Although superficial vein thrombosis (SVT) has traditionally been viewed as a benign disease, it is associated with an increased risk of deep-vein thrombosis (DVT). However, there are almost no data to suggest which patients may be at increased risk of subsequent DVT following SVT.

In this week's issue of Blood, Roach and colleagues analyze results from a case-controlled study of nearly 5,000 individuals with DVT and more than 5,700 controls to determine how previous SVT could influence DVT risk in the setting of other risk factors. Consistent with previous data, patients with previous SVT had a nearly six-fold increased risk of developing DVT than the control group; however, the relative risk increased with the addition of certain risk factors ranging from obesity, smoking, and immobilization to oral contraceptives, hormonal therapy, and pregnancy.

Although data are insufficient to change practice, they may begin to identify groups of patients with prior SVT in whom thromboprophylaxis should be considered.

The risk of venous thrombosis in individuals with a history of superficial vein thrombosis and acquired venous thrombotic risk factors, Rachel E. J. Roach, Willem M. Lijfering, Astrid van Hylckama Vlieg, Frans M. Helmerhorst, Frits R. Rosendaal, and Suzanne C. Cannegieter, Blood - doi: 10.1182/blood-2013-07-518159