The study involving over 6,195 patients was conducted by the University of Minnesota, University of Basel, Switzerland and Columbia University in the US. It found that patients who were on prescribed blood thinners before contracting covid-19 were admitted less often to the hospital, despite being older and having more chronic medical conditions than their peers.

The study, claimed to be the largest in the world on the role of blood thinners in covid-19 cases, evaluated all patients over the age of 18 years who were diagnosed with covid-19 in a prospective cohort study from 4 March to 27 August, 2020. The study was based on data from 12 hospitals and 60 clinics of M Health Fairview, a non-profit that operates an integrated health system based in Minneapolis, US.

The scientists investigated the relationship between 90-day anticoagulation therapy among out-patients before covid-19 diagnosis and the risk for hospitalization and mortality and inpatient anti-coagulation therapy and mortality risk.

“Blood thinners — regardless of if they are being used before being infected with covid-19 or started when admitted to the hospital for treatment of covid-19 — reduce deaths by almost half,” the study said, adding that hospitalized covid-19 patients benefit from blood thinners regardless of the type or dose of the medication used.

According to scientific evidence, some people with covid-19 develop abnormal blood clots, including in the smallest blood vessels. The clots may also form in multiple places in the body, including in the lungs. This unusual clotting may cause different complications, including organ damage, heart attack and stroke. 

Researchers said that the clotting may be triggered by the high levels of inflammation caused by the SARS-CoV-2 infection. A high level of inflammation can affect multiple organs and result in severe disease. People who already have damage to the blood vessels from diabetes or high blood pressure may be at a higher risk of developing blood clots, said the scientists.

“We know that covid-19 causes blood clots that can kill patients. But, do blood thinners save lives in covid-19? Blood thinners are medications prescribed to prevent blood clots in patients with a prior blood clot in their lungs or legs. They also prevent blood clots in the brain secondary to abnormal heart rhythms, like atrial fibrillation. Blood thinners are the standard of treatment in these diseases, which is why we looked at data to see if it impacted hospitalizations related to covid-19,” said lead author Sameh Hozayen, an assistant professor of medicine at the University of Minnesota Medical School.

“We already know that overwhelmed hospitals have a higher risk for death among their patients, so reducing hospitalization may have a positive impact during a covid-19 surge,” Hozayen said.

Hozayen also noted that about half of patients who are being prescribed blood thinners for blood clots in their legs, lungs, abnormal heart rhythms or other reasons, do not take them. “By increasing adherence for people already prescribed blood thinners, we can potentially reduce the bad effects of covid-19,” Hozayen said.

“At most centres around the world now, there are protocols for starting blood thinners when patients are first admitted to the hospital for covid-19 — as it is a proven vital treatment option. Outside of covid-19, the use of blood thinners is proven to be lifesaving for those with blood coagulations conditions,” Hozayen said.