One of the big bets in the pandemic and still used by doctors in the treatment of Covid, the anticoagulants they do not bring any benefit to patients with mild and moderate forms of the disease.
The conclusion is a study multicenter of Coalizão Covid-19, a research alliance involving several Brazilian institutions, which tested the outpatient use of anticoagulation. The work was published in the June issue of The Lancet.
The results have caused repercussions in the international scientific community because, during the pandemic, many doctors adopted routine treatment anticoagulantseven without scientific evidence to support the conduct.
In the new study, 660 outpatients were followed. Half of them received anticoagulant and the other, placebo and routine care for symptomatic Covid patients.
The study investigated whether 10 mg of rivaroxaban once daily for 14 days would reduce the risk of venous thromboembolic events, need for mechanical ventilation, heart attack, stroke (cerebrovascular accident), acute limb ischemia or death from Covid-19 in these patients.
The results showed that there was no significant difference between the group that used rivaroxaban and the control group.
“In addition to our study, we did a meta-analysis, and there is no benefit. Based on the existing evidence, there is no indication of anticoagulating an outpatient with a diagnosis of Covid”, says cardiologist Álvaro Avezum, director of the International Research Center at Hospital Oswaldo Cruz (SP) and main author of the study.
The doctor says that, from the point of view of safety, there was nothing to justify not indicating the medication. “Was there excessive bleeding? No. [a não indicação] It was due to lack of effectiveness.”
Covid-19 is associated with an increased risk of arterial and venous thrombosis, and studies have already shown that anticoagulants reduce the risk of thromboembolism in critically ill hospitalized patients. But so far there is nothing new, because it is already routine to administer anticoagulants to patients admitted to ICUs to reduce the risk of thrombosis.
According to him, during the pandemic, many professionals used anticoagulation in out-patients off-label because they inferred, even without scientific evidence, that it would prevent thrombotic events associated with Covid.
“They also measured clotting markers, such as D-dimer, and if they had increased, they saw rationale for using [a anticoagulação]. That’s wrong too, I didn’t have data for that. It was all very much based on pathophysiology [condições observadas durante um estado de doença] and beliefs.”
The cardiologist reinforces that the guidance not to treat mild Covid patients with anticoagulants is restricted to cases where there is no previous indication for the use of the medication.
In Avezum’s opinion, the study is important to guide medical practices. “It is much more useful for us to confirm that there is no indication and stop using it. It is a lesson for people not to keep using promising treatments. Promising is unproven, it is just a stage, and not the end in itself. Promising has to convert in proof, which was not the case [da anticoagulação].”
According to doctor and researcher Raphael Prudente, who also participated in the study, even today there are colleagues recommending anticoagulation to Covid outpatients, even without the support of science.
“[o pensamento é] We are going to anticoagulate because, the sooner we anticoagulate, the more we avoid thrombosis and other repercussions of the disease.”
For him, the response of the non-benefit of the medication brought by the study is as important as if it had been favorable to its use. “It’s great if anticoagulation improves, but it’s also great that I know I can’t use it. It was like that with azithromycin, ivermectin and hydroxychloroquine [medicações sem evidências de benefícios para Covid].”
According to Prudente, the results also serve to alert the population about the importance of relying on medical practices based on scientific protocol. “During the pandemic, we saw a lot of conduct that made no sense and we are still seeing the effects today. Vaccines are being thrown in the trash because people are not immunizing themselves.”