New research suggested that the COVID-19 infection is linked to hypercoagulability or the increased tendency of the blood to clot.
The study published in the journal EClinical Medicine by The Lancet. It found that blood clots led to an increased risk of death by 74 per cent.
The study was led by researchers from UC San Diego Health.
For the study, the researchers reviewed 42 different studies involving more than 8,000 patients diagnosed with COVID-19.
Using random models, the team produced summary rates and odds ratios of mortality in COVID-19 patients with thromboembolism, blood clots. They then compared them to patients without these conditions to determine what effect blood clots may have on the risk of death.
Lead author, Mahmoud Malas, MD, division chief of Vascular and Endovascular Surgery at UC San Diego Health said: "We began to notice a really unusual manifestation of venous and arterial thromboembolism in patients with COVID-19.”
Malas added: "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. It's unusual because we have never seen anything like this with other respiratory infections."
The study noted that overall, 20 per cent of the COVID-19 patients were found to have blood clots in the veins. This gets increased for patients who are admitted to the intensive care unit. That statistic increased to 31 per cent.
The authors of the study explained that blood clots in the vein can reach the lungs and develop into a pulmonary embolism, resulting in a higher risk of death. Furthermore, blood clots in the arteries may lead to limb amputation if not treated surgically in time.
"The collective experience in the literature as captured in this meta-analysis study brings additional light on the importance of blood vessel clotting events in hospitalized patients with COVID-19," said Bryan Clary, MD, surgeon-in-chief at UC San Diego Health and co-author of the study.
He added: "While the frequency of these events is much higher than expected, our study likely underestimates the incidence of thromboembolism in the global population of patients with COVID-19, including non-hospitalized patients."
According to Malas, the rate of clotting in COVID-19 patients is higher than what is reported for other viral pandemics, including the H1N1 influenza of 2009.
The researchers mentioned that for coronavirus patients, blood clots can appear in either veins or arteries.
Now, clinical trials are being conducted to understand how blood thinners can mitigate the risk of clotting in patients with COVID-19.
Malas concluded: "What we can learn from this paper is due diligence. We're still in the process of understanding the pathophysiology of COVID-19, so it's important to have a low index of suspicion when it comes to this infection to ensure we're doing all we can to mitigate the spread and prevent severe outcomes."