One of the most important tasks for physicians treating a patient who has experienced a first unprovoked pulmonary embolism is determining how long the patient must remain on oral anticoagulants, according to a presentation Wednesday at CHEST 2013, the annual conference of the American College of Chest Physicians.
“The physician should always perform a prompt review of the patient’s total risk profile, and find the point where the risk of recurrence crosses the risk of bleeding,” said Lisa Moores, MD, associate dean for student affairs at the the Uniformed Services University for the Health Sciences in Bethesda, Maryland.
Moores’ presentation, “Duration of Anticoagulation in VTE: The Patient Has a Say,” focused on events that were not provoked by circumstances such as surgery, bed-bound hospitalization, lengthy air travel, pregnancy, or oral contraceptives.
The task of balancing the competing primary outcomes, bleeding and recurrent PE, while challenging, has been made easier by research published in the literature in recent years,as researchers have identified a number of risk factors to make the decision easier, Moores said.
According to one study by Rodgers et al. published in Blood Reviews
in 2010, 1.6% of patients would die from recurrent embolism in eight years of follow-up, while between 0.9 and 2.4% of patients would die from a major bleed over the same period of time.
Therefore, high-risk patients should remain on oral anticoagulants, while three months treatmet may suffice for those with a lesser risk, said Moores, who explained that treatment for six or 12 months is any more effective at preventing recurrence than treatment for three months, Moores said.
In the same article, Rodgers identified a number of measures to identify patients with more than 3% annual risk of recurrence, including abnormal measurements of the blood clot fragment D-dimer and residual thrombosis. Patients with proximal deep vein thrombosis were also twice as likely as those with distal thrombosis to have a recurrent event, Moores noted.
“Many newer studies have gotten into the habit of measuring a patient’s D-dimer level before stopping therapy, so as not to put the patient at risk,” she added. A systematic review of seven studies, including 1,888 patients, found that those with abnormal levels of D-dimer had an 8.9% annual risk of recurrence, compared to 3.5% in those without, according to Moores.
Another study, which looked at 600 patients in Canada, found that no combination of factors could predict which men would have less than 3% risk of annual recurrence, while in women, factors such as age, D-dimer, and the ‘HER’ factors (standing for hyper-pigmentation, edema, and redness of leg) were predictive factors, Moores explained. Those women with one or fewer risk factors had a 1.6% annual risk of occurrence, while those with two or more risk factors has an annual risk of recurrence of 14.1%, she added, noting that according to this formula, 52% of women with a first unprovoked pulmonary embolism were classified in the low risk group.