Various studies of patients with venous thromboembolism (VT) have shown that 1–1.5 months of anticoagulant therapy is associated with a higher risk of recurrent VT after cessation of the therapeutic regimen than 3–6 months of treatment. The shortest duration of anticoagulation therapy that is associated with the lowest possible risk of recurrence, however, is unclear. By analyzing pooled data from seven trials, Florent Boutitie et al. have now shown that discontinuing treatment after more than 3 months has no benefit over halting therapy at the 3-month mark.

The meta-analysis included data from 2,925 patients (mean age 60.7 years), of whom 25% had been anticoagulated for 1 or 1.5 months after VT, 36% had been treated with anticoagulation therapy for 3 months, 27% had been treated for 6 months, and 12% had been anticoagulated for 12 or 27 months.

As expected, the rate of recurrent VT during the first 24 months after anticoagulation was highest for patients who had received therapy for only 1 or 1.5 months (10.0 per 100 patient-years). Rates of recurrent VT in the patients who received 3, 6, or 12 or 27 months anticoagulation therapy did not substantially differ from each other (6.8, 7.0, and 7.5 per 100 patient-years, respectively). Compared with patients who had been treated for longer, the higher risk of recurrent VT in those treated for only 1 or 1.5 months (hazard ratio [HR] 1.52, 95% CI 1.14–2.02, P = 0.004) was only apparent in the first 6 months of the 24-month period (HR 2.12, 95% CI 1.43–3.15, P <0.001); after 6 months, risk was comparable with that of patients who had been treated for longer (HR 1.05, 95% CI 0.69–1.59, P = 0.83).

The investigators conclude that “if patients with VT do not have an indication for indefinite anticoagulant treatment, they generally should stop treatment at 3 months.”