The multicentre MICHELLE trial found that thromboprophylaxis with rivaroxaban over 5 weeks after discharge was beneficial for COVID-19 patients. Individuals with moderate to high-risk scores for venous thromboembolism (VTE) had a 67% risk reduction in a composite of various clinical outcomes.
The MICHELLE trial (NCT04662684) was designed to explore a possible advantage of prolonged antithrombotic prophylaxis with rivaroxaban for COVID-19 patients after discharge from hospital1. The randomised controlled, open-label study, analysed 318 patients that were allocated to treatment with 10 mg of rivaroxaban daily or placebo over 35 days. All adult COVID-19 patients previously received a standard dose thromboprophylaxis during a hospital stay ≥3 days and presented a risk score of ≥4 or a risk score of 2/3 with an initial D dimer >500 ng/mL in the modified IMPROVE VTE.
The primary outcome consisted of a composite of several clinical and imaging-based parameters (i.e. symptomatic VTE, VTE-related death, VTE detected at bilateral lower limb venous duplex scan and CT-pulmonary angiogram, symptomatic arterial TE, myocardial infarction, non-haemorrhagic stroke, major adverse limb event, cardiovascular death). The baseline characteristics were overall balanced in the study arms. Mean age was between 56.4 and 57.8 years, around 40% were women, and 37.7–38.4% had an IMPROVE VTE score of ≥4.
The results of the primary outcome revealed a relative risk reduction of 67% for those receiving rivaroxaban (95% CI 0.13–0.90; P=0.03) compared with placebo. The corresponding number needed to treat equalled 16. “When we broke down the components of the primary outcome, we could see that the primary outcome occurrence was basically driven by pulmonary embolism, either asymptomatic or symptomatic and fatal pulmonary embolism in the control group,” said Professor Eduardo Ramacciotti (Santa Casa School of Medicine, Brazil). In the matter of safety, major bleedings happened in neither study arm, and event rates were low in both groups, even for a composite of adverse consequences due to major, non-major and other bleedings (rivaroxaban 2.51%; placebo 1.89%).
“In patients discharged after hospitalisation due to COVID-19 with increased IMPROVE score, thromboprophylaxis with rivaroxaban 10 mg once daily for 35 days improved clinical outcomes without increasing bleeding, compared with no out-of-hospital anticoagulation,” Prof. Ramacciotti concluded.
Note:
1. Ramacciotti E. The Michelle trial: Medically ill hospitalized patients for COVID-19 thrombosis extended prophylaxis with rivaroxaban therapy. Late-breaking trials – COVID 19, ESC Congress 2021, 27–30 August.