Over 10% of lower extremity DVT cases isolated to calf
MedWire News: More than one in 10 cases of lower extremity deep vein thrombosis (DVT) are isolated to the distal calf, results of a community-based study show.
Furthermore, patients with isolated calf DVT are twice as likely as those with proximal DVT to experience recurrence or extension within 2 weeks, possibly because they are less likely to receive anticoagulation therapy or an inferior vena cava (IVC) filter, report Frederick Spencer (McMaster University, Hamilton, Ontario, Canada) and colleagues in the Journal of Thrombosis and Thrombolysis.
The researchers reviewed the medical records of residents of the Worcester (Massachusetts, USA) metropolitan area (population approximately 500,000) and identified 1495 individuals with independently validated lower extremity DVT in 1999, 2001, 2003, or 2005.
Of these, 166 (11.1%) were diagnosed with isolated calf DVT, while the remainder had proximal DVT.
Compared with patients who had proximal DVT, those with isolated calf DVT were an average of 8 years younger (57.3 vs 65.5 years), and were less likely to present with an unprovoked VTE (19.9 vs 28.8%), or have a prior history of DVT or pulmonary embolism (PE; 10.8 vs 22.6%), a recent severe infection (9.6 vs 22.2%), recent heart failure (10.2 vs 16.8%), or a history of cerebrovascular disease (5.4 vs 12.8%).
By contrast, rates of recent surgery and recent fracture were higher in isolated calf DVT patients than in proximal DVT patients, at 34.9% versus 24.8% and 21.1% versus 9.9%, respectively.
In terms of treatment practices, patients with isolated calf DVT were less likely to be discharged on anticoagulants or with an IVC filter than patients with proximal DVT (84.1 vs 92.3%).
The overall rates of recurrent venous thromboembolism (VTE; DVT and PE) did not differ significantly between patients with calf DVT and proximal DVT at 30 days (7.6 vs 4.1%), 6 months (11.0 vs 8.7%), or 1 year (11.0 vs 11.5%), but patients with calf DVT had a significant 2.3-fold higher adjusted risk for early (14-day) VTE recurrence or extension than those with proximal DVT.
Spencer and colleagues say their data indicates that "there is ample room for improvement in the management of isolated calf DVT by community practitioners."
"Indeed, we found that almost one in every six patients were not discharged on anticoagulant therapy or with an IVC filter from their initial hospital encounter. Calf DVTs are still considered 'benign' by many practitioners and it is not uncommon for physicians to withhold anticoagulant treatment in these patients," they write.
The team concludes that further study of management strategies for isolated calf DVT is needed to provide guidance to physicians involved in the management of these patients.
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By Laura Cowen