Understanding the increased risk of thrombosis in COVID-19 patients

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Patients with COVID-19 have a substantially increased risk of thrombosis, even when treated with antithrombotic therapy.

A team led by Prof. Ton Lisman at the Department of Experimental Surgery of the University Medical Center in Groningen, last year started studying the underlying mechanisms leading to this thrombotic risk. Their study started on a small cohort of COVID-19 patients seen by their collaborators at the Hospital Clinic Barcelona in Spain. Their results, published in the Journal of Thrombosis and Haemostasis in August 2020, showed that these patients treated with antithrombotic drugs still have ongoing activation of coagulation, suggesting that an alternative therapy is urgently needed. Since then, the group together with their collaborators have collected many data on patients cohorts and published several papers.

To gain more insight, the group is collaborating with the Karolinska Institute in Stockholm (Sweden) and with the University of North Carolina at Chapel Hill (North Carolina, USA). In collaboration with these institutes, last year the group published three papers on hemostatic changes in relation to disease severity and outcome in a cohort of 100 patients with COVID-19 (Research and Practice in Thrombosis and Haemostasis, Arteriosclerosis, Thrombosis, and Vascular Biology 1, Arteriosclerosis, Thrombosis, and Vascular Biology 2), confirming and extending previous findings.

Additional studies in this cohort have been published this year and are clarifying more and more the mechanisms causing the increased thrombotic risk in COVID-19 patients (COVID-19 is Associated with an Acquired Factor XIII Deficiency, Sustained prothrombotic changes in COVID-19 patients 4 months after hospital discharge, Elevated factor V activity and antigen levels in patients with Covid-19 are related to disease severity and 30-day mortality). One of the recent publications highlights the long-term changes in the clotting system in COVID-19 patients (after 4 months) which may contribute to the so-called ‘long-Covid syndrome’. 

The studies from Prof. Lisman’s group and his collaborators are still in progress and will hopefully inspire future research to help improve antithrombotic management of COVID-19 patients, as highlighted in their recent letter in Lancet Haematology (Sustained prothrombotic changes in convalescent patients with COVID-19).