Risk of recurrence after discontinuing anticoagulation in patients with COVID-19- associated venous thromboembolism: a prospective multicentre cohort study

Background: The clinical relevance of recurrent venous thromboembolism (VTE) after discontinuing anticoagulation in patients with COVID-19-associated VTE remains uncertain. We estimated the incidence rates and mortality of VTE recurrences developing after discontinuing anticoagulation in patients with COVID-19-associated VTE. Methods: A prospective, multicenter, non-interventional study was conducted between March 25, 2020, and July 26, 2023, including patients who had discontinued anticoagulation after at least 3 months of therapy. All patients from the registry were analyzed during the study period to verify inclusion criteria. Patients with superficial vein thrombosis, those who did not receive at least 3 months of anticoagulant therapy, and those who were followed for less than 15 days after discontinuing anticoagulation were excluded. Outcomes were: 1) Incidence rates of symptomatic VTE recurrences, and 2) fatal PE. The rate of VTE recurrences was defined as the number of patients with recurrent VTE divided by the patient-years at risk of recurrent VTE during the period when anticoagulation was discontinued. Findings: Among 1106 patients with COVID-19-associated VTE (age 62.3 ± 14.4 years; 62.9% male) followed-up for 12.5 months (p25-75, 6.3-20.1) after discontinuing anticoagulation, there were 38 VTE recurrences (3.5%, 95% confidence interval [CI]: 2.5-4.7%), with a rate of 3.1 per 100 patient-years (95% CI: 2.2-4.2). No patient died of recurrent PE (0%, 95% CI: 0-7.6%). Subgroup analyses showed that patients with diagnosis in 2021-2022 (vs. 2020) (Hazard ratio [HR] 2.86; 95% CI 1.45-5.68) or those with isolated deep vein thrombosis (vs. pulmonary embolism) (HR 2.31; 95% CI 1.19-4.49) had significantly higher rates of VTE recurrences. Interpretation: In patients with COVID-19-associated VTE who discontinued anticoagulation after at least 3 months of treatment, the incidence rate of recurrent VTE and the case-fatality rate was low. Therefore, it conceivable that long-term anticoagulation may not be required for many patients with COVID-19-associated VTE, although further research is needed to confirm these findings. Funding: Sanofi and Rovi, Sanofi Spain