The meta-analysis of data from 27 studies with 17,202 patients was published in the Annals of Internal Medicine. According to two of the paper’s coauthors, Faizan Khan, MSc, and Marc A. Rodger, MD, it “provides best available estimates of long-term bleeding risk with different anticoagulants in patients with unprovoked VTE,” including subgroups at increased risk.
Patients at increased risk for major bleeding include those who are older; those using antiplatelet therapy; and patients with kidney disease, a history of bleeding, or anemia, noted the coauthors, who work for the Ottawa Hospital Research Institute.
The researchers focused on randomized controlled trials (RCTs) and prospective cohort studies that reported major bleeding among patients with a first unprovoked or weakly provoked VTE who received oral anticoagulation for at least 6 months beyond an initial anticoagulant treatment course of at least 3 months.
The investigators analyzed data from 14 RCTs and 13 cohort studies. In all, 9,982 patients received a vitamin K antagonist (VKA), and 7,220 received a direct oral anticoagulant (DOAC).
The incidence of major bleeding per 100 person-years was 1.7 events with VKAs, compared with 1.1 events with DOACs. The researchers estimated that the 5-year cumulative incidence of major bleeding with VKAs was 6.3%. The available data for DOACs were insufficient to estimate the incidence of major bleeding beyond 1 year.
“This information can help clinicians counsel patients and inform shared decision-making about extended therapy,” the researchers said.
Risks of serious bleeding ‘not trivial’
Margaret Fang, MD, with the University of California, San Francisco, agreed that the study can help clinicians and patients weigh the risks of extended anticoagulation for common types of VTE.
The study also “highlights that the risks of serious bleeding are not trivial” and points out gaps in the literature regarding the long-term use of DOACs for extended VTE therapy, Dr. Fang said.
Better ways to predict which patients will develop bleeding on anticoagulants are needed, Dr. Fang added. “It will also be important to establish which of the various therapies for preventing recurrent VTE – full dose versus lowered dose, or even aspirin – has the best balance of safety and efficacy,” she said.
‘Standardized approach’ for identifying high-risk patients lacking
Clinical practice guidelines recommend indefinite anticoagulation for an unprovoked VTE, except when patients are at high risk of bleeding, the authors noted. But clinicians lack a “standardized approach to identify patients at high risk of bleeding,” Mr. Khan and Dr. Rodger said. “Evidence from randomized trials on net long-term benefit of extended therapy is limited, and current guideline recommendations are largely based on expert consensus opinion. Major bleeding events are two to three times more likely to be fatal than recurrent VTE events, so extended therapy is not always associated with a net mortality benefit, particularly in patients at low risk of recurrent VTE or high risk of bleeding.”