While respiratory issues continue to be the most common symptom of a COVID-19 infection, the disease could also be linked to an increased tendency of the blood to clot.
In a new study, researchers found that blood clots led to an increased risk of death by 74%.
The research was conducted by a team from UC San Diego Health.
In the study, the team reviewed 42 different studies involving more than 8,000 patients diagnosed with COVID-19.
Using random models, they produced summary rates and odds ratios of mortality in COVID-19 patients with thromboembolism, blood clots—and compared them to patients without these conditions to determine what effect blood clots may have on the risk of death.
They noticed a really unusual manifestation of venous and arterial thromboembolism in patients with COVID-19.
Arterial thromboembolism is a serious condition that occurs when a blood clot blocks blood flow in an artery.
In addition to higher instances of blood clots, the mortality for patients hospitalized for COVID-19 and with thromboembolism was much higher, compared to patients without clots.
Overall, 20% of the COVID-19 patients were found to have blood clots in the veins, and among patients in the intensive care unit, that number increased to 31%.
The team says blood clots in the vein, or deep vein thrombosis, can reach the lungs and develop into pulmonary embolism, resulting in a higher risk of death.
Blood clots in the arteries may lead to limb amputation if not treated surgically in a timely fashion.
While the frequency of these events is much higher than expected, this study likely underestimates the incidence of thromboembolism in the global population of patients with COVID-19, including non-hospitalized patients.
According to the team, arterial blood clots developing in people with the flu is extremely rare, and the rate of clotting in patients with COVID-19 is higher than what is reported for other viral pandemics, including the H1N1 influenza of 2009.
Similar symptoms are shared between influenza and SARS-CoV-2, such as fever, cough, shortness of breath, or fatigue.
Blood clotting can occur in patients hospitalized with the flu, but only in veins. For patients with COVID-19, blood clots can appear in either veins or arteries.
Typically, clotting in the arteries is caused by health factors, such as atrial fibrillation, high blood pressure, high cholesterol, diabetes, or lifestyle choices like smoking.
Patients who are hospitalized for long periods of time are also more at risk for blood clots in the vein due to immobility.
Blood clots in the vein are treated or prevented with prescribed blood thinners.
Proactively administering such medications to hospitalized patients can also help prevent clots from forming.
Clinical trials are ongoing to determine how blood thinners can reduce the risk of clotting in patients with COVID-19.
One author of the study is Mahmoud Malas, MD, the division chief of Vascular and Endovascular Surgery.
The study is published in EClinical Medicine.
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