Study Confirms Efficacy of Blood Thinners as Potential Therapeutic Treatment for COVID-19

A study based on a new international clinical trial has offered additional data on the efficacy of blood thinners for COVID-19 and insight on best potential regimens.

Early in the COVID-19 pandemic, researchers from the Mount Sinai Health System (New York, NY, USA) showed that anticoagulation therapy was associated with improved survival among hospitalized COVID-19 patients. However, there were questions about the size of the potential benefit and the dosage of the therapy for improving its effectiveness. The researchers conducted an observational study by evaluating the electronic medical records of 4,389 confirmed COVID-19-positive patients. The study was an extension of Mount Sinai research that showed that treatment with anticoagulants was associated with improved outcomes both in and out of the intensive care unit among hospitalized COVID-19 patients. The work was prompted by the discovery that many patients hospitalized with COVID-19 developed high levels of life-threatening blood clots.


For their observational study, the researchers specifically looked at survival and death rates for patients placed on therapeutic and prophylactic doses of blood thinners (oral antithrombotics, subcutaneous heparin, and intravenous heparin) versus those not placed on blood thinners. The researchers used a hazard score to estimate risk of death, which took relevant risk factors into account before evaluating the effectiveness of anticoagulation, including age, ethnicity, pre-existing conditions, and whether the patient was already on blood thinners. The researchers also took into account and corrected for disease severity, including low oxygen saturation levels and intubation.

They found that all regimens of anticoagulants, or drugs that prevent blood clotting, were far superior to no anticoagulants in COVID-19 patients. More specifically, patients on both a “therapeutic” or full dose, and those on a “prophylactic” or lower dose, showed about a 50% higher chance of survival, and roughly a 30% lower chance of intubation, than those not on anticoagulants. They observed that therapeutic and prophylactic subcutaneous low-molecular weight heparin, and therapeutic oral apixaban may lead to better results. Separately, the researchers looked at autopsy results of 26 COVID-19 patients and found that 11 of them (42%) had blood clots-pulmonary, brain, and/or heart-that were never suspected in the clinical setting. These findings suggest that treating patients with anticoagulants may be associated with improved survival and clinicians should evaluate patients on an individual basis given the benefit-risk tradeoff.

“Clearly, anticoagulation is associated with improved outcomes and bleeding rates appear to be low,” said corresponding author Anu Lala, MD, Assistant Professor of Medicine (Cardiology) and Director of Heart Failure Research at the Icahn School of Medicine at Mount Sinai. “As a clinician who has treated COVID-19 patients on the front lines, I recognize the importance of having answers as to what the best treatment for these patients entails, and these results will inform the design of clinical trials to ultimately give concrete information.”

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