Genetic risk factor for clotting after COVID-19 infection

Which people who catch COVID-19 have a higher risk of
developing blood clots? A Monash-Baker study investigated.

With blood clots caused by COVID-19 already associated with a higher risk of death, it is important to understand which groups are vulnerable and how best to treat them. 

New information is emerging on COVID-associated blood clots in people with inherited thrombotic conditions such as the common Factor V Leiden, which affects about in one in every 20 or 25 people in Australia.

A paper published in Circulation by researchers from Monash University, the Baker Heart and Diabetes Institute and The Alfred, highlights that genetic thrombotic conditions, including the Factor V Leiden mutation, are associated with a higher risk of COVID-19 venous thromboembolism (a blood clot that starts in the vein), and could be useful in assessing risk of developing blood clots during COVID-19 infection.

A large cohort was studied from the UK Biobank, with more than 13,712 individuals aged 45-69 years and who subsequently tested positive to COVID-19 between January 2020 and May 2021 included in the study. COVID-19 venous thromboembolism (VTE) was identified in 197 cases and there were 890 deaths from COVID-19, with COVID-19 VTE associated with higher COVID-19 deaths.

The risk of venous blood clots during COVID-19 infection can be influenced by many variables, including age, gender, or contraceptive use. Researchers and haematologists, Dr Hannah Stevens and Associate Professor James McFadyen believe the identification of novel risk factors, such as genetic thrombophilias, may help to stratify patients with a higher risk of developing COVID-19 associated blood clots. 

They say that almost all patients with COVID-19 admitted to hospitals receive medication to prevent blood clots. With significant interest in the optimal dose and duration of blood thinner medications for the prevention of COVID-19 thrombotic complications, they say this study may help identify a group of patients who need higher dose blood thinner medications.

Dr Stevens said, "We also found an association with a genetic risk score, which evaluates multiple genetic variants. So we know now that several inherited variants, such as the Factor V Leiden mutation, increase risk of COVID-19 associated blood clots, and this is an important piece of the puzzle. This has never been described in COVID-19."

The researchers are also involved in clinical trials to understand more. A/Prof McFadyen is involved in the ASCOT clinical trial which aims to generate clinical evidence about new treatments for COVID-19 to reduce death or the need for mechanical ventilation in hospitalised patients. This includes investigating anticoagulation therapies which aim to reduce the risk of blood clots associated with the COVID-19 infection.            

Reference 

Stevens H, Canovas R, Tran H, Peter K, McFadyen JD. Inherited Thrombophilias Are Associated With a Higher Risk of COVID-19-Associated Venous Thromboembolism: A Prospective Population-Based Cohort Study. Circulation. 2022 Mar 22;145(12):940-942. doi: 10.1161/CIRCULATIONAHA.121.057394. Epub 2022 Mar 21. PMID: 35312380; PMCID: PMC8928846. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.057394