Patients with provoked VTE often on anticoagulation longer than recommended
Three variables were associated with receiving anticoagulation for longer than three months after a provoked venous thromboembolism (VTE): direct oral anticoagulant use, history of VTE, and history of myocardial infarction.
Most patients with a provoked venous thromboembolism (VTE) received anticoagulation for longer than the guideline-recommended three months, a study found.
The multicenter retrospective cohort study looked at anticoagulation duration for patients enrolled in the Michigan Anticoagulation Quality Improvement Initiative registry who were receiving anticoagulation for a provoked VTE. The registry gathers data from six centers that manage patients' long-term anticoagulation. Four hundred seventy-four patients on warfarin and 302 patients on direct oral anticoagulants (DOACs) (half of whom were taking apixaban) for a primary indication of provoked VTE between 2008 and 2020 were included in the study. Results were published Oct. 26 by the Journal of the American Heart Association.
Patients on DOACs were more likely than those on warfarin to be treated for more than 120 days. Patients on warfarin were more likely than those on DOACs to receive less than 80 days of treatment. The median (25th to 75th percentile) length of treatment was 142 (91 to 234) days for patients taking warfarin and 180 (101 to 360) days for those taking DOACs. Recurrent VTE (odds ratio [OR], 2.75; 95% CI, 1.67 to 4.53), history of myocardial infarction (OR, 3.92; 95% CI, 1.32 to 11.7), and direct oral anticoagulant rather than warfarin use (OR, 2.22; 95% CI, 1.59 to 3.08) were independently associated with prolonged anticoagulation.
Deep venous thrombosis (DVT) was the primary indication for anticoagulation in 363 (76.6%) patients on warfarin and 172 (57.0%) patients on DOACs (P<0.001). Pulmonary embolism, with or without concurrent DVT, was the primary indication in 111 (23.4%) patients on warfarin and 130 (43.1%) patients on DOACs. Of the patients on DOACs, 16 (5.3%) were transitioned to a reduced DOAC dose at some point after initiating anticoagulation, 12 (4.0%) after three months of anticoagulation.
A total of 88 (18.6%) patients on warfarin and 15 (5.6%) patients on DOACs had a history of VTE (P<0.001), and 25 (5.3%) patients on warfarin and 36 (11.9%) patients on DOACs had bleeding within 30 days of VTE (P<0.001). Other comorbid conditions did not differ statistically between groups. Surgery was the provoking condition in 394 (83.1%) patients on warfarin and 208 (68.9%) patients on DOACs (P<0.001), and oral contraceptives were the provoking condition in 44 (9.3%) patients on warfarin and 59 (19.5%) patients on DOACs (P<0.001). Rates of casting/lower extremity immobilization and childbirth as the provoking incident were not statistically different between groups.
The study highlights the risks of prolonged anticoagulation and the potential benefit of early identification and intervention, the study authors said, calling for clinicians to be aware of the risk when prescribing and managing anticoagulation. They also noted that VTE management has changed markedly over the past decade. “Newer trials of extended therapy with DOACs describe a decreased risk of VTE without increased bleeding risk even beyond the initial 3-month period,” the authors wrote. “These new trials could explain why the majority (215, 71.2%) of patients in our study received longer than guideline-recommended therapy, or why 12 (4.0%) were changed to a reduced dose at 3 months but continued anticoagulation.”