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Anticoagulation for deep vein thrombosis (DVT) in the calf reduces risk that the clot will propagate and may improve other clinical outcomes as well, according to a meta-analysis.

Patients who received vitamin K antagonists or heparin had dramatically lower rates of pulmonary embolism and clot propagation compared with those who went without anticoagulants, Randall R. De Martino, MD, of Dartmouth-Hitchcock Medical Center in Lebanon, N.H., and colleagues found.

Mortality rates tended to favor anticoagulation in this population as well, although not significantly and with evidence of heterogeneity among the studies (odds ratio 0.57, 95% confidence interval 0.06 to 5.6), the group reported at the Society for Vascular Surgery's Vascular Annual Meeting in Chicago.

"Patients may benefit from treatment with anticoagulants," De Martino told 麻豆传媒.

But physicians still have to determine need for treatment on a case-by-case basis taking risk factors like hypercoagulability and mobility into account, he cautioned.

"None of these studies are going to be able to adequately dictate practice guidelines," he noted in an interview, pointing to the low quality of the available research and few cases of pulmonary embolism that made firm conclusions difficult.

Calf vein DVT is considered less life-threatening than more proximal iliac or femoral vein DVTs, De Martino noted. And because it is less common and less studied as well, there's little consensus on optimal management, he explained.

So De Martino's group conducted a systematic review of the evidence for anticoagulation in treatment of calf DVT.

Among the more than 2,300 studies they found on the topic, they pooled the results of eight studies in adults with ultrasound- or venogram-confirmed calf DVT who were followed for at least one month after treatment with an anticoagulant for at least 30 days or no anticoagulation.

These studies included two randomized controlled trials and six cohort studies with a total of 126 patients who received a vitamin K antagonist or heparin and 378 who got no anticoagulant.

Anticoagulant treatment was associated with an 88% reduced rate of pulmonary embolism (odds ratio 0.12, 95% confidence interval 0.02 to 0.77, P=0.03) and a 71% reduced rate of clot propagation overall (OR 0.29, 95% CI 0.14 to 0.62, P=0.04).

Only one study reported on post-thrombotic syndrome and found no treatment effect.

Treatment-related complications, such as bleeding, have been poorly documented as well, De Martino's group noted.

Bleeding appeared to be 1.6 times more common with anticoagulation, but the wide confidence interval and significant heterogeneity among the three studies that reported these events precluded any firm conclusions, they cautioned.

Even among their narrow selection of studies, most were of poor methodological quality, they cautioned.

"The way in which the patients were assessed and their follow-up monitoring was less than optimal," De Martino told 麻豆传媒. "More robust clinical studies will be necessary."

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