Being obese may double the risk of needing hospital treatment for the coronavirus, according to a major study.
British scientists trawled through data for more than 428,000 people who were part of the UK Biobank.
Some 340 of those tested positive for COVID-19 in hospital – one of the only places to access a test in the UK – amid the pandemic.
Being overweight or obese increased the risk of ending up in hospital with the killer infection by 1.6-fold and 2.3-fold, respectively.
And for every BMI increase of four-and-a-half units, the risk of dying from COVID-19 rose by about 25 per cent, Glasgow University experts said.
Obesity leads to conditions such as type 2 diabetes and heart disease, both of which are known to make patients more vulnerable to COVID-19.
But extra fat may also lead to inflammation within the body, heavily linked to grave complications. An overproduction of inflammatory markers results in what has been described as a ‘cytokine storm’, which can be deadly for coronavirus patients.
Other scientists have suggested fat cells harbour vital immune cells needed to fight the infection, or make large amounts of a protein used by the virus to latch on to human cells.
The findings uncovered several other risk factors for hospitalisation with COVID-19, including smoking, being of BAME background and sleep apnoea.
Being overweight or obese increased the risk of ending up in hospital with the killer infection by 1.6-fold and 2.3-fold, respectively. Other important findings included that black people have a 2.7-fold higher risk of testing positive for the virus in hospital, while the risk for people of South Asian descent was 1.3-fold higher
Being overweight or obese increased the risk of ending up in hospital with the COVID-19 by 1.6 or 2.3 times, respectively, University of Glasgow found (stock)
The team took their data from the UK Biobank, which recruited 37-70 year olds in 2006-2010 from the general population.
BMI, smoking status, walking pace – a measure of fitness, ethnicity and any health conditions were collected at the time.
The recent outcome of a confirmed positive COVID-19 test, given by Public Health England, was provided and compared with the Biobank data.
The preliminary results showed that extra weight was a risk factor for ending up in hospital with COVID-19.
While being overweight rose the risk by 60 per cent, being underweight led to a small increased risk of five per cent.
Lead researcher Dr Paul Welsh said although obese people are more likely to end up in hospital with COVID-19, the differences in BMI ‘is part of the picture, but certainly not all of it’.
He told MailOnline: ‘I think the study adds to the picture we are getting from a range of different sources that people who have a higher body mass index are a bit more likely to get more severe symptoms, and to require medical attention.
‘What we see in this study from a general population is that it’s a graded association.
‘It’s not that there is a threshold of “obesity” beyond which the risk suddenly goes up, it looks like the more body fat, the higher the risk of testing positive in a hospital setting.
‘[It] indicates that the patient is probably getting symptoms that mean they seek healthcare. So it’s a pretty consistent picture.’
Dr Welsh added that the paper had not been peer-reviewed by other scientists. It is published on the pre-print site medRxiv.
He said the link between obesity and COVID-19 was still there after taking into account co-founders such as age, ethnicity, and socioeconomic factors.
FAT CELLS ARE A TARGET FOR THE VIRUS, EXPERTS SAY
The reason why obese people may be more at risk of dying from coronavirus could be because their fat cells make large amounts of a protein used by the infection to infiltrate human cells.
In a ‘perspective’ paper published in the journal Obesity , the researchers explained the link between obesity and COVID-19 that has emerged.
The coronavirus – scientifically called SARS-CoV-2 – latches onto ACE-2 receptors, known as the ‘gateway’ into cells inside body.
Dr Ilja Kruglikov of Wellcomet GmbH in Germany, wrote ACE-2 is ‘widely expressed’ in fat cells called adipocytes in obese people and type 2 diabetics.
Fat might therefore ‘serve as a viral reservoir’, warned Dr Kruglikov and his colleague Philipp Scherer of the University of Texas Southwestern Medical Center, Dallas.
The scientists also explained that fat cells may drive the production of a type of cell called myofibroblasts.
Myofibroblasts are a major driver of pulmonary fibrosis – scarring of the lung tissue which reduces the organs function and oxygen intake.
Infected patients have been found to have pulmonary fibrosis in their lungs, but it was likely already present before they became ill.
The risk of pulmonary fibrosis, which develops over time, increases with age. It is especially high in people over the age of 65.
The scar tissue can destroy the normal workings of the lungs and make it hard for oxygen to get into the blood, causing shortness of breath.
The presence of pulmonary fibrosis is ‘likely to influence the clinical severity of COVID-19’, the scientists said.
Some researchers now believe diabetes drugs could be used to fight the infection – and admitted that losing weight may also have a benefit.
The evidence is not concrete but data from hospitalised COVID-19 patients suggests obese people are more likely to die than those who are slim.
Although the data had been collected 10 years ago, Dr Welsh said the information was likely to be the same now.
People tend to stay in rank order over their life course for BMI with only a small proportion changing.
Body mass index (BMI) is calculated by dividing weight in kilograms by height in metres squared.
Around three in ten adults in England are clinically obese – a BMI above 30. The rate is among the highest in the Western world.
According to data from NHS hospitals, 75 per cent of COVID-19 patients in intensive care are overweight, compared with 65 per cent in the general population.
Dr Welsh and colleagues explained low-grade inflammation from extra fat is probably a key underlying reason for overweight people developing severe COVID-19 complications.
An increase in circulating inflammatory markers can negatively impact on the immune system and metabolic health, the team said.
Cytokines are normal chemical-signalling molecules which guide a healthy immune response.
But in abundance, they could lead to a ‘cytokine storm’ – when the immune system goes into overdrive and starts attacking healthy tissue.
It’s known to play a major role in some COVID-19 deaths by causing multi-organ failure.
The Glasgow team added that obesity increases thrombosis, which is relevant considering an emerging link between COVID-19 and deadly blood clots.
Other important findings included that black people have a 2.7-fold higher risk of testing positive for the virus in hospital, while the risk for people of South Asian descent was 1.3-fold higher.
Coronavirus has claimed more than 30,000 lives in the UK already – and a concerning high proportion of them are from BAME groups.
A government review is analysing how factors including obesity, ethnicity and gender can affect the impact of the virus on people’s health.
Yesterday, Health Secretary Matt Hancock said ‘the age profile and factors like obesity’ should be taken into account when considering the UK’s shocking death toll.
The Glasgow analysis found both men and ‘ever smokers’ had 60 per cent higher odds of testing positive in hospital, and the risk increased by 10 per cent for every five years of age.
Men have been repeatedly flagged as more at risk than women, which could be due to genetic differences, scientists say.
The coronavirus – scientifically called SARS-CoV-2 – latches onto ACE-2 receptors, known as the ‘gateway’ into cells inside body. Fat cells ‘widely express’ ACE-2 receptors, which may explain the link between obesity and severe COVID-19, according to researchers who wrote a ‘perspective’ paper published in the journal Obesity yesterday
Researchers at New York University recently highlighted obesity as a main driver of patients under the age of 60 needing hospital care. The team found those with a BMI between 30 and 34 were almost twice as likely to be admitted to acute or critical (ICU) care than those with a BMI under 30. This likelihood increased to 3.6 times in those patients with a BMI of 35 or more
WHY MIGHT OBESE PEOPLE MORE AT RISK OF BECOMING VERY ILL FROM COVID-19?
Studies have shown obese people are more likely to suffer serious complications or die from infections, such as the flu.
Doctors say the immune systems of fat people are constantly ramped up as they try to protect and repair the damage inflammation causes to cells.
Using all its energy fending off inflammation means the body’s defence system has few resources left to defend against a new infection like COVID-19.
Dr Dyan Sellayah, a lecturer in cellular and organismal metabolism, University of Reading, said obese people tend to have dysfunctional immune systems.
‘Their fat tissue for example becomes a reservoir for immune cells known as macrophages. While these cells reside in our fat under normal circumstances, in obesity they are at higher frequency and become more troublesome (they start to secrete inflammatory cytokines) and negatively impact on immune and metabolic health.’
Obese people might eat a diet with very little fiber and antioxidants – which keep the immune system healthy – such as fruit and vegetables.
Most patients with a BMI of over 40 suffer from breathing problems that range from simple shortness of breath to a potentially life-threatening condition known as obesity hypoventilation syndrome (OHS).
Excess weight also makes it more difficult for the diaphragm and lungs to expand and inhale oxygen. Starved of oxygen, organs will begin to fail.
These factors may explain why obese people’s lungs tend to fail faster when the new coronavirus strikes, compared to a healthy person.
COVID-19 kills by spreading deep into the lungs and causing complications such as pneumonia.
There are several other factors that may increase an obese person’s chance of falling seriously ill with coronavirus, including a lack of exercise.
Studies have shown that physical activity increases the numbers of certain immune cells that help to bolster immune activity.
Clogged up arteries also make it hard for blood carrying immune cells to pass through and repair cells around the body.
But the evidence on smoking is less clear. Contrary to popular scientific belief, evidence is beginning to emerge that smoking could protect against the coronavirus.
A review of 28 papers by University College London academics found the proportions of smokers among hospital patients were ‘lower than expected’.
When smokers do get diagnosed with the virus, however, they appear to be more likely to get so sick that they need ventilation, two studies in the review showed.
Public health professors say there is ‘something weird going on with smoking and coronavirus‘ and are struggling to explain the connection.
Dr Welsh said: ‘Lower risk in people with better physical fitness and those who don’t smoke – this probably gives these people better lung function to cope with the infection.’
Meanwhile anyone who already has a pre-existing health condition, and therefore a compromised immune system, has been warned to be extra stringent with social distancing measures due to COVID-19 risks.
Echoing previous research, the Glasgow team found that high blood pressure, heart disease and diabetes doubled the risk of hospitalisation with COVID-19.
Chronic obstructive pulmonary disease (COPD) raised the risk by almost three times, and sleep apnoea, a common sleep disorder, by almost four times, and chronic kidney disease by almost five.
Obesity is a known risk factor for several chronic health conditions including type 2 diabetes, stroke, heart attack and even certain types of cancer.
But alarming data is showing being overweight is an independent risk factor – possibly the biggest vulnerability for people under 60.
A study last week of 17,000 coronavirus admissions found that death rates were 37 per cent higher among obese patients.
Scientists are exploring a range of theories to explain the link. Yesterday, two academics from Germany and the US said it could be because fat cells express high levels of ACE-2, which is dubbed the ‘gateway’ for the virus to infiltrate cells.
Other scientists have pointed towards the low-grade inflammation issue, and the impact of weight on internal organs.
The weight of stomach fat pushes the diaphragm upwards, reducing lung volume.
COVID-19 is a respiratory disease which in severe cases, affects lung function. Therefore restricted lung capacity would exacerbate symptoms.
If lung function has already deteriorated, oxygen in the blood is of limited supply which can affect vital organs, such as the heart.
According to a report on intensive care patients in the UK, people of a healthy weight make up a minority of critically ill COVID-19 patients. Almost three quarters are carrying extra weight (BMI of 25 to 40+)
Contrary to popular scientific belief, evidence is beginning to emerge that smoking could protect against the coronavirus. A review of 28 papers by University College London academics found the proportions of smokers among hospital patients were ‘lower than expected’
WHAT IS THE EVIDENCE THAT OBESITY IS A RISK FACTOR FOR COVID-19?
There have been no studies which clearly mark the largest risk factors for COVID-19 – the disease caused by SARS-CoV-2.
But, using data from hospitals, researchers are able to identify which conditions are common among those who are frequently in hospital with the disease.
One study in New York City, the world’s coronavirus hotspot, found obese people were more likely to be hospitalised with the coronavirus than cancer or lung disease patients who have compromised immune systems.
The ‘surprising’ findings also showed that even smoking wasn’t a predictor of hospitalisation like obesity was, despite the habit being bad for the lungs.
The researchers at the NYU Grossman School of Medicine, who analysed hospital reports of 4,103 COVID-19 positive patients, found is that ‘in the decision tree for admission, the most important features were being over 65 and obesity.’
Researchers at New York University recently highlighted obesity as a main driver of patients under the age of 60 needing hospital care.
They looked at the records of 3,615 patients who tested positive between March 4 and April 4.
The team found those with a BMI between 30 and 34 were almost twice as likely to be admitted to acute or critical (ICU) care than those with a BMI under 30.
This likelihood increased to 3.6 times in those patients with a BMI of 35 or greater, according to the findings published in Clinical Infectious Diseases.
In patients over 60 years, the researchers didn’t find a significant link between obesity and severe illness that needed critical care.
One study by US health officials, which recorded the weights of 178 patients, found obesity was the most common underlying condition for patients aged under 65 who were admitted to hospital for COVID-19.
Of those aged between 18 and 49 who had a health condition, obesity accounted for 60 per cent. The second most common condition was asthma, at 27 per cent.
For those between 50 and 64 years of age with an underlying health problem, obesity accounted for 49 per cent – more than the 47 per cent who had high blood pressure.
Comparatively, according to data from the UK’s National Health and Nutrition Examination Survey, age-adjusted obesity prevalence is 42 per cent.
In the UK, according to data from hospitals, almost 75 per cent of COVID-19 patients in intensive care are overweight, compared with 65 per cent in the general population.
The analysis of 17,000 COVID-19 admissions found death rates were 37 per cent higher among obese patients, second only to dementia (39 per cent) but more than heart disease (31 per cent).
The research was conducted by a team of Britain’s top infectious diseases scientists who are part of the pandemic-planning global body.