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People discharged from hospital after being treated for COVID-19 have increased rates of organ damage, readmission and death, compared to the general population. New research suggests that COVID-19 might place a greater burden on healthcare systems than was previously thought.

COVID-19 is known to affect the respiratory system. Increasing evidence suggests it also affects other organs, such as the kidneys, liver and heart. But before this study, it was unclear how many people experience organ damage. 

This study looked at the extra long-term burden on healthcare systems caused by COVID-19. Researchers analysed data on people who had been treated for COVID-19 in hospital. Their health was compared to people in the general population of the same age and with similar medical history.

More than 1 in 10 people treated in hospital for COVID-19 died after they were discharged, the study found. Nearly 1 in 3 were readmitted. They were more likely to develop respiratory disease, cardiovascular disease and diabetes than people in the general population.

More research is needed to understand which groups of people are most likely to develop these complications, the researchers say.

They suggest that an integrated care is needed to diagnose, treat and prevent organ damage after COVID-19. This approach means that the same medical team provides care at all stages of a patient's illness, in hospital and in the community.

Further information on long COVID is available on the NHS website.

What’s the issue?

COVID-19 is known to cause respiratory symptoms and damage the lungs. There is increasing evidence that the disease can also affect the heart, kidney, liver and other organs.

Medical professionals and the public are now aware of long COVID (post COVID syndrome) in which unexplained signs and symptoms continue for 12 weeks or more after infection. However, few studies on long COVID have looked at organ damage beyond the lungs (multiorgan dysfunction). This study set out to address the gap in knowledge.

What’s new?

Researchers looked at the medical records of almost 50,000 people who were hospitalised in England with COVID-19, and discharged. Each was matched to somebody who had not been infected with COVID-19. These controls were the same age, sex and ethnicity, and had a similar medical history. 

The research team gathered information on hospital admission or readmission, and death from any cause. They looked at new diagnoses of respiratory, cardiovascular, metabolic, kidney and liver diseases. The data covered 140 days on average for each patient. 

The researchers found that, compared to matched controls, COVID-19 patients: 

    • were 4 times more likely to be admitted to hospital; nearly 1 in 3 were readmitted (after the initial discharge)
    • were 8 times more likely to die; more than 1 in 10 died
    • were 27 times more likely to have a new diagnosis of a respiratory disease
    • were 3 times more likely to have a new diagnosis of diabetes
    • had a higher risk (50% higher) of a new diagnosis of heart disease.

The increased risk of diabetes and heart disease supports other evidence that COVID-19 damages many organs, not just the lungs.

People who were under 70 or from ethnic minority groups were badly affected after hospital treatment for COVID-19. They were compared, respectively, to the over 70s or to White people in the general population. The under 70s and people from ethnic minority groups had greater increases in risk of death, hospital admission and disease beyond the lungs. 

Why is this important?

In this study, people discharged from hospital after COVID-19 had higher rates of organ damage than similar individuals in the general population. The authors say the diagnosis, treatment and prevention of long COVID therefore needs to be more holistic. It should not focus on a specific organ or symptom. 

The researchers suggest that healthcare professionals look to good examples of integrated care pathways to guide the management of long COVID in future. For instance, clinicians in London and Hertfordshire developed a model for treating the long term lung condition, chronic obstructive pulmonary disease (COPD). The same medical team provides care at all stages of the patient's condition. They found that it improved continuity of care and effective communication between professionals and patients. Compared to standard care, it reduced hospital stays and readmission rates. 

There have been more than 8 million confirmed cases of COVID-19 in the UK. Many more had COVID-19 without being admitted to hospital. Some who had less severe infection also experience long COVID. Organ damage is only part of the problem; many people have other ongoing problems. These include loss of taste and smell, and severe fatigue, which can be debilitating. 

This study suggests that the long-term burden of COVID-19 infection could be substantial for healthcare systems. It adds to the challenge of addressing inequalities in health and providing high quality care for people with long-term conditions.

What’s next?

The study suggests that people hospitalised with COVID-19 have an increased risk of readmission and death. They are more likely to have damage to the lungs and other organs. These increased risks do not just affect older people. 

Better understanding of the risk factors for long COVID could lead to improved treatments and prevention efforts for those with an increased risk of organ damage after being hospitalised with coronavirus. 

The study prompted further research which is ongoing at the University of Cambridge. A clinical trial called HEAL-COVID is also studying people discharged from hospital after COVID-19. They will receive either apixaban (which prevents blood clots), or atorvastatin (which lowers bad cholesterol). Researchers want to see whether either of these treatments reduce the risk of hospital readmission, cardiovascular disease, or death. 

You may be interested to read

This NIHR Alert is based on: Ayoubkhani D, and others. Post-COVID syndrome in individuals admitted to hospital with covid-19: retrospective cohort study. BMJ 2021;372:n693

A linked editorial about the burden of long COVID: Sivan M, and others. Fresh evidence of the scale and scope of long COVID. BMJ 2021;373:n853

Information on HEAL-COVID, the clinical trial aiming to identify beneficial treatments for people discharged from hospital after recovering from COVID-19.


Funding: The study received no external funding. 

Conflicts of Interest: One of the authors has received funding unrelated to this study from AstraZeneca.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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Study authors

This research points to a more chronic picture of COVID-19. It is another reason to take suppressing the virus seriously. We must stop thinking of this as just an acute infectious disease. You might not see post-COVID complications on the government’s coronavirus dashboard, but the numbers are stark. I had to ask my co-author Daniel Ayoubkhani to recheck the data several times because I just didn’t believe it. The findings show that we need to monitor and follow up people who were hospitalised with COVID-19. It is not an option to just discharge them and not see them again.  The study would not have been possible if healthcare data wasn’t as available and accessible as it is. One of the biggest strengths of doing research in the UK is access to NHS datasets. It means we can answer questions like this in near-real time.Amitava Banerjee, Professor of Clinical Data Science and Honorary Consultant Cardiologist, UCL "This was one of the largest studies to date to examine the downstream consequences of severe COVID-19. It was made possible by linking anonymised medical records in a safe and secure NHS research environment. The rates of post-hospitalisation organ damage – not just in the lungs but across the body – are stark, and the increase in risk was not confined to older people. The findings add to our understanding of the long-term implications of the pandemic for patients, health services and society more broadly."Daniel Ayoubkhani, Principal Statistician, Office for National Statistics, Newport, UK

Lived experience

As a person whose life was completely changed by a COVID infection, I find this study highly informative, and to some degree validating of my own experience. My concern is that it focuses only on hospitalised patients. Many people were very unwell at home but weren’t tested, especially during the first wave of the pandemic in the UK. I am left with permanent lung damage and an autoimmune disease, but, sadly, these will never be part of the statistics.In my professional capacity as a nurse, this evidence will help me in discussions with patients. It will also help me advocate for better patient care. I would really like to see all patients treated with a high level of caution after COVID-19, irrespective of the severity of the initial infection. An interesting finding is that patients admitted to intensive care had lower rates of death compared to patients admitted to wards. This could be because they are offered more extensive follow up and rehabilitation after they leave hospital. Any problems can be detected and acted on early. COVID-19 should be considered a risk factor for a number of complications, not an explanation of ongoing symptoms. I hope that guidelines will recommend that GPs investigate persistent complaints, rather than watching and waiting. I expect this research to raise awareness of the long-term consequences of a COVID infection and to inform health behaviours such as vaccination choice, and protection measures. I hope that it will help society to better understand the full impact the disease can have on an individual.Nora Dimitrova, Research Nurse, University Hospital Southampton (currently on long-term sick leave)

Member of the public

This paper could affect public perception of the virus at a time where many people are erring towards learning to live with COVID. Younger groups especially may be surprised by the data and how COVID could potentially affect their long-term quality of life.This paper could increase the attention given to post-COVID syndrome. The current focus is very much on hospitalisation and death figures which clearly do not give the full picture.  I believe the public should be armed with as much information as possible in order to decide for themselves how to deal with this unique situation. We are very much still learning about the longer-term consequences of the virus.Nicky Chinneck, Public Contributor, Liskeard, Cornwall 

Clinical pharmacist 

This paper highlights the need for integrated care to tackle post-COVID syndrome. As a clinical pharmacist, I act as a bridge between patients and physicians. I play a crucial role in devising treatment plans for patients.This study provides a strong base for the urgent research required to establish the risk factors and assessment tools for developing appropriate health policies on management of post-COVID syndrome.Post-COVID syndrome is a huge burden on patients and health care professionals and will also have a toll on the economy. With proper guidelines in place, we can prevent post-COVID syndrome and save valuable health funds.Kabir Manchanda, Clinical Pharmacist, Shree Mahant Inderesh Hospital, Dehradun, Uttarakhand, India 
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