VTE recurrence risk varies according to initial risk factors
MedWire News: The risk for recurrent venous thromboembolism (VTE) is lower when the index case is provoked by surgery rather than a transient nonsurgical risk factor, results of a systematic review show.
Even so, the recurrence risk among patients with VTE provoked by a nonsurgical transient risk factor was still lower than that in patients with unprovoked VTE, and was low enough to justify stopping anticoagulant therapy at 3 months in most patients, as recommended by current guidelines, say the researchers.
"It has recently been recognized that the presence or absence of a transient, or reversible, risk factor at the time of VTE strongly affects the risk of recurrence after anticoagulant therapy is stopped," note Alfonso Iorio (McMaster University, Hamilton, Ontario, Canada) and colleagues.
To quantify this risk, Iorio and team carried out a systematic review of studies that reported the risk for VTE recurrence after stopping anticoagulant therapy among patients with a first episode of symptomatic VTE provoked by any reversible risk factor.
They also compared the risk for recurrence according to whether VTE was associated with recent surgery or with a transient nonsurgical risk factor.
Among 15 prospective cohort studies and randomized trials of patients treated for VTE for at least 3 months, the researchers identified 150 (6.6%) recurrent VTEs in 2268 patients during the 0- to 24-month interval after stopping anticoagulant therapy, corresponding to an annualized event rate of 3.3% per patient-year.
When the patients were divided into those with surgical and nonsurgical risk factors, the event rates were 0.7% and 4.2% per patient-year, respectively.
In the same studies the researchers also identified 321 recurrent VTEs in 2174 patients with unprovoked VTE, corresponding to an event rate of 7.4% per patient- year.
"The risk of recurrence is low if VTE is provoked by surgery, intermediate if provoked by a nonsurgical risk factor, and high if unprovoked," write Iorio and co-authors in the Archives of Internal Medicine.
"These risks affect whether patients with VTE should undergo short-term versus indefinite treatment," they conclude.
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By Laura Dean