COVID-19 infection increases the risk of life-threatening blood clots for at least 49 weeks , according to a new study of health records from 48 million unvaccinated adults from the first wave of the pandemic.
Background:
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection induces a prothrombotic state, but the long-term effects of COVID-19 on the incidence of vascular diseases are unclear.
Methods:
We studied vascular disease after COVID-19 diagnosis in population-wide, anonymized linked English and Welsh electronic health records from January 1 to December 7, 2020. We estimated adjusted hazard ratios comparing the incidence of arterial thrombosis and Venous thromboembolic events (VTE) after COVID-19 diagnosis with incidence in people without COVID-19 diagnosis. We performed subgroup analyzes by COVID-19 severity, demographic characteristics, and prior history.
Results:
Among 48 million adults, 125,985 were hospitalized and 1,319,789 were not hospitalized within 28 days of COVID-19 diagnosis. In England, there were 260,279 first arterial thromboses and 59,421 first VTEs during 41.6 million person-years of follow-up.
Adjusted hazard ratios for first arterial thrombosis after COVID-19 diagnosis compared with no COVID-19 diagnosis decreased from 21.7 (95% CI, 21.0–22.4) at week 1 after of COVID-19 diagnosis to 1.34 (95% CI, 1.21–1.48) during weeks 27 to 49.
Adjusted hazard ratios for first VTE after COVID-19 diagnosis decreased from 33.2 (95% CI, 31.3–35.2) at week 1 to 1.80 (95% CI, 1. 50–2.17) during weeks 27 to 49 hazard ratios were higher, for longer after diagnosis, after hospitalized vs. non-hospitalized COVID-19, among black or Asian people vs. white people, and between people without a previous event versus people with a previous event.
The estimated total population increases in risk of arterial thrombosis and VTE 49 weeks after COVID-19 diagnosis were 0.5% and 0.25%, respectively, corresponding to 7,200 and 3,500 additional events, respectively. after 1.4 million COVID-19 diagnoses.
Conclusions:
The high relative incidence of vascular events shortly after COVID-19 diagnosis decreases more rapidly for arterial thromboses than for VTE. However , the incidence remains high up to 49 weeks after COVID-19 diagnosis . These results support policies to prevent severe COVID-19 through COVID-19 vaccines, early post-discharge screening, risk factor control, and use of secondary preventive agents in high-risk patients.
Clinical Perspective What’s new? In a cohort study of 48 million adults in England and Wales, COVID-19 was associated with a substantial excess incidence of both arterial thrombosis and venous thromboembolism, which decreased over time since COVID-19 diagnosis. The excess incidence was higher, for a longer time, after hospitalized than not hospitalized for COVID-19. There were an estimated 10,500 excess arterial thromboses and venous thromboembolic events following 1.4 million COVID-19 diagnoses. What are the clinical implications? Strategies to prevent vascular events after COVID-19 are particularly important after severe COVID-19 leading to hospitalization and should include early screening in primary care and risk factor management. After severe COVID-19, people at high risk of vascular events should be prescribed preventive therapies and counseled on the importance of compliance. New simple treatment strategies are needed to reduce infection-associated venous thromboembolism and arterial thromboses. |
Comments
The findings suggest that the COVID-19 pandemic may have led to an additional 10,500 cases of heart attacks, strokes and other blood clot complications, such as deep vein thrombosis, in England and Wales alone in 2020, although the excess risk for people remains small and reduces over time.
The research, which involved a large team of researchers led by the Universities of Bristol, Cambridge and Edinburgh, and Swansea University, shows that people with mild or moderate disease were also affected. The authors suggest that preventative strategies, such as giving high-risk patients medications to lower blood pressure, could help reduce cases of serious clots.
Researchers studied population-wide anonymized electronic health records in England and Wales from January to December 2020 to compare the risk of blood clots after COVID-19 with the risk at other times. Data were accessed securely through the NHS Digital Trusted Research Environment for England and the SAIL Databank for Wales.
In the first week after a COVID-19 diagnosis, people were 21 times more likely to have a heart attack or stroke, conditions that are primarily caused by blood clots that block arteries. This reduced to 3.9 times more likely after 4 weeks.
Researchers also studied conditions caused by blood clots in the veins: these include deep vein thrombosis and pulmonary embolism, a clot in the lungs that can be fatal. The risk of blood clots in the veins was 33 times higher in the first week after a COVID-19 diagnosis. This reduced to an eight-fold increased risk after four weeks.
The increased risk of blood clots after COVID-19 remained throughout the duration of the study, although between weeks 26 and 49 it dropped to 1.3 times more likely to have clots in the arteries and 1.8 times more likely to have clots in the arteries. in the veins.
Most previous research studied the impact of COVID-19 on blood clotting in people hospitalized with COVID-19. The new study shows that there was also an effect in people whose COVID-19 did not lead to hospitalization , although their excess risk was not as great as that of those who had severe illness and were hospitalized.
The authors say the risk of blood clots for people remains low. In people at highest risk (men over 80 years of age), an additional 2 men out of every 100 infected may have a stroke or heart attack after COVID-19 infection.
The data analyzed was collected in 2020, before the launch of mass vaccination in the UK and before newer COVID-19 variants such as Delta and Omicron became widespread. Researchers are now studying data beyond 2020 to understand the effect of vaccination and the impact of newer variants.
The research is published in the journal Circulation and was supported by the BHF Data Science Center at Health Data Research UK , the National Longitudinal COVID-19 Health and Wellbeing Core Study, the National Data and Connectivity Core Study and the CONVALESCENCE study of long COVID.
Jonathan Sterne, professor of medical statistics and epidemiology at the University of Bristol, director of the NIHR Bristol Biomedical Research Center and director of Health Data Research UK South West, who co-led the study, said: "We are reassured that the risk is decreasing quite quickly, particularly for heart attacks and strokes, but the finding that it remains elevated for some time highlights the long-term effects of COVID-19 that we are only beginning to understand.”
Angela Wood, professor of biostatistics at the University of Cambridge, associate director of the British Heart Foundation’s Data Science Center and co-leader of the study, said: "We have shown that even people who were not hospitalized faced an increased risk of clots. of blood in the first wave While the risk to people remains small, the effect on public health could be substantial and strategies to prevent vascular events will be important as we progress through the pandemic.”
Dr William Whiteley, a clinical epidemiologist and neurologist at the University of Edinburgh, who co-led the study, said: "The effect that coronavirus infection has on the risk of blood clot-related conditions is understudied and methods based on “Evidence to prevent these conditions after infection will be key to reducing the effects of the pandemic on patients.”
