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Decision rule helps identify women at low risk for recurrent VTE
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Women with one or fewer risk factors for recurrent thromboembolism may safely discontinue anticoagulant therapy after five to seven months, according to recent data.
Researchers from the University of Ottawa and other sites in Canada developed a clinical decision rule for women being treated with anticoagulants following an unprovoked thromboembolism.
They evaluated 600 participants prescribed oral anticoagulation therapy for five to seven months after their event. The mean age of participants was 53 years. Participants were seen in clinic every six months during the study. Researchers determined whether patients had one or more of the following risk factors: hyperpigmentation; edema or redness of the leg; D-dimer ≥250 mcg/L while on warfarin; BMI ≥30 kg/m2 or age ≥65 years.
After the discontinuation of therapy, the researchers reported 91 cases of recurrent venous thromboembolism during follow-up (annual risk, 9.3%; 95% CI, 7.7%-11.3%).
Women with zero or one of the risk factors had an annual risk of 1.6% (95% CI, 0.3%-4.6%). The annual risk for women with two or more of the above characteristics was 14.1% (95% CI, 10.9%-17.3%).
Among men, the annual risk was 13.7% (95% CI, 10.8%-17%), though the researchers were unable to identify a low-risk subset due to a lack of clinical predictors to satisfy their criteria.
CMAJ. 2008;179:417-426.