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Patient Evidence Summary
Doctor, I have been admitted to hospital and have COVID-19. What is my risk of developing blood clots after hospital discharge?
For patients who are hospitalized with COVID-19, the risk of developing symptomatic blood clots in the 3 months after hospital discharge is low. For this reason, there is likely no benefit in routinely taking anticoagulants for prevention of blood clots due to COVID-19, if you weren't already taking them prior to being admitted. However, you should follow any instructions given to you about anticoagulants by your doctor.
Study highlights
About 1 out of every 100 people who were hospitalized with COVID-19 infection developed a symptomatic blood clot within 3 months of hospital discharge. About 1 to 2 out of every 100 people had bleeding that required medical care during this period. These findings suggest that anticoagulants should not be routinely given to every patient who is discharged home after admission to hospital with COVID-19 infection.
This study may not apply to all patients hospitalized with COVID-19 because the severity of COVID-19 infection has changed over time, and around one-third of patients in this study did not require oxygen or devices to help them breathe, suggesting they had mild COVID-19 infection.
Understanding the problem
Patients admitted to hospital for any reason are at higher risk of developing VTE, and COVID-19 infection further increases this risk, especially among people who are severely ill. Current guidelines recommend the use of anticoagulants for prevention of VTE for all hospitalized patients with COVID-19 during their hospital stay. However, whether they would benefit from anticoagulation after discharge for VTE prevention is less clear.
The researchers wanted to study how often patients who are hospitalized and have COVID-19 infection develop VTE or bleeding in the 90 days after hospital discharge to better understand whether anticoagulation should be routinely prescribed during this period.
Who? The study included 513 adults (average age 58 years) who were hospitalized with COVID-19 infection or were diagnosed with COVID-19 during their hospital stay between January 2021 and October 2022. All included patients had COVID-19 infection confirmed using a laboratory test. Patients who were already receiving treatment with anticoagulation at hospital discharge were excluded from the study.
What? The study assessed the rate of new symptomatic VTE, including DVT and PE, with virtual follow-up at 30 and 90 days after hospital discharge. The study also assessed the rate of bleeding and death from any cause within 90 days of hospital discharge.
Risk of venous thromboembolism, bleeding, and death in people who were hospitalized and had COVID-19
Outcomes at 90 days following hospital discharge | Rate of events among all patients (n=513) | Rate of events excluding patients on treatment dose of anticoagulation (n=510) | Rate of events excluding patients on any dose of anticoagulation (n=477) |
|---|---|---|---|
Symptomatic venous thromboembolism | About 1 out of 100 people | About 1 out of 100 people | About 1 out of 100 people |
Major bleeding | 0 out of 100 people | 0 out of 100 people | 0 out of 100 people |
| Clinically relevant non-major bleeding | About 2 out of 100 people | About 2 out of 100 people | About 1 out of 100 people |
| Death from any cause | 3 out of 100 people | 3 out of 100 people | 3 out of 100 people |
This Evidence Summary is based on the following article:
Siegal DM, Arsenault MP, Abdulrehman J, et al. Venous thromboembolism after hospitalization for COVID-19: venous thrombosis virtual surveillance in COVID study. J Thromb Haemost. 2025 Aug;23(8):2550-2557. doi: 10.1016/j.jtha.2025.04.018. Epub 2025 Apr 25. PubMed
Meha Bhatt, MD, MSc
Meha is a PGY2 internal medicine resident at McMaster University, where she also completed her Master's in Health Research Methodology. She completed medical school at Queen’s University. Her interests include hematology as well as health services research, global health, and social medicine.
Siraj Mithoowani, MD, MHPE, FRCPC, FACP
Siraj Mithoowani is an Assistant Professor in the Department of Medicine, McMaster University, and is a clinical hematologist at St. Joseph's Healthcare, Hamilton. He specializes in the care of non-malignant and thrombotic blood disorders. His research interests are in venous thromboembolism and postgraduate medical education.
Published: Wednesday, October 15, 2025
Please note that the information contained herein is not to be interpreted as an alternative to medical advice from a professional healthcare provider. If you have any questions about any medical matter, you should consult your professional healthcare providers, and should never delay seeking medical advice, disregard medical advice or discontinue medication based on information provided here.
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, McMaster University