Life-threatening blood clots persist for at least 49 weeks after COVID-19

COVID-19 infection increases the risk of potentially life-threatening blood clots for at least 49 weeks, according to a new study of the health records of 48 million unvaccinated adults from the first wave of the pandemic. When.

The findings suggest that the COVID-19 pandemic may have caused an additional 10,500 heart attacks, strokes and other thrombotic complications. deep vein thrombosis Although there has been an increase in 2020 alone in England and Wales, the excess risk to individuals remains small and will decrease over time.

The study, which involved a large research team led by the Universities of Bristol, Cambridge, Edinburgh, and Swansea, showed that people with mild or moderate illness were also affected. The authors suggest that preventive strategies, such as giving high-risk patients blood pressure-lowering drugs, may help reduce cases of severe blood clots.

Researchers examined anonymized electronic health records for the entire population of England and Wales from January to December 2020 and compared the risk of blood clots after COVID-19 to risks at other times. Data were accessed safely and securely via the NHS Digital Trusted Research Environment in England and the SAIL Databank in Wales.

In the first week after being diagnosed with COVID-19, people were 21 times more likely to have a heart attack or stroke. Heart attacks and strokes are mainly caused by blood clots blocking arteries. This dropped him to 3.9 times as likely after four weeks.

Researchers have also studied conditions caused by blood clots in veins. These include deep vein thrombosis and pulmonary embolism. Pulmonary thrombus is fatal. In his first week after being diagnosed with COVID-19, his risk of developing blood clots in his veins was 33 times higher. This lowered him to eight times the risk after four weeks.

The high risk of post-COVID-19 blood clots remained for the duration of the study, but by weeks 26 to 49 there was a 1.3-fold reduction in the likelihood of arterial thrombosis and a 1.8-fold reduction in the likelihood of venous thrombosis.

Most previous studies have studied the effects of COVID-19 on blood clotting in people hospitalized with COVID-19. A new study shows that COVID-19 also affected people who weren’t hospitalized, but the excess risk wasn’t as great as for those who were seriously ill and were hospitalized.

The authors say the risk of blood clots for individuals remains low. Among those most at risk, men over the age of 80, 2 out of 100 infected men are likely to have a stroke or heart attack after being infected with COVID-19.

The data analyzed was collected in 2020, before the mass vaccination rollout in the UK and before the spread of the latest COVID-19 variants such as Delta and Omicron. Researchers are now studying data from 2020 onwards to understand the effects of vaccination and the impact of new variants.

The research is published in the journal circulation It was also supported by the BHF Data Science Center at Health Data Research UK, the Longitudinal Health and Wellbeing COVID-19 National Core Study, the Data and Connectivity National Core Study, and the CONVALESCENCE study for long-term COVID.

Jonathan Stern, Professor of Medical Statistics and Epidemiology at the University of Bristol, Director of the NIHR Bristol Center for Biomedical Research, and Director of the Health Data Institute for the South West of England, who co-led the study, said: says. Although very rapid, especially in the case of heart attacks and strokes, the finding that it remains elevated for some time highlights the long-term effects of COVID-19 that we are only beginning to understand.”

We have shown that even those who are not hospitalized have an increased risk of blood clots in the first wave. Strategies to prevent vascular events will be critical to surviving the pandemic. “

Angela Wood, Professor of Biostatistics, University of Cambridge, Deputy Director, British Heart Foundation Data Science Center, Co-Chief Researcher

Dr. William Whiteley, a clinical epidemiologist and neurologist at the University of Edinburgh, who co-led the study, said, “The impact of coronavirus infection on the risk of blood clot-related conditions has not been well studied. Evidence-Based Prevention Methods These conditions after infection will be key to reducing the impact of the pandemic on patients.”