The Emerging Link Between Obesity and COVID-19

New research indicates that COVID-19 can take a more severe course in those who are obese, including younger people.

As the nation works toward controlling the coronavirus pandemic, scientists and researchers are racing to find out everything they can about the virus and who is most vulnerable. New evidence suggests that obesity is a risk factor for COVID-19, according to researchers at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine. The research also suggests that young people who are obese — whether they have other health issues or not — are especially at risk.

The data, published in the New England Journal of Medicine on April 17, looked at the first 393 consecutive patients with COVID-19 who were admitted to NewYork-Presbyterian/Weill Cornell Medical Center and NewYork-Presbyterian Lower Manhattan Hospital from March 3 to March 27. Obesity was defined as a body-mass index of 30 or higher, and 136 of the patients were in that category.

“We started this registry of patients so that we could help answer some tough questions that front-line healthcare workers were grappling with,” says Dr. Monika Safford, chief of the Division of General Internal Medicine at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine, and the senior author of the report. “Our goal was to inform physicians about which types of patients are likely to not do well, using data. This effort would not have been possible without the collaborative work of physicians, researchers, and Weill Cornell Medicine’s medical students.”

Health Matters spoke with Dr. Safford to understand what this research means for patients and the general public.

What is significant about this research?
The preliminary data confirms what many doctors and front-line staff have been saying, that many of their patients who are severely ill with COVID-19 are obese. What’s rather striking about the data we have compiled is that the obesity prevalence seems to be the greatest in people under the age of 65: Of the patients studied, almost half under the age of 65 are obese. We’re also seeing cardiovascular problems such as high blood pressure and coronary artery disease as risk factors. So, what is happening here? That is a big puzzle that needs a lot more work.

Dr. Monika Safford

What surprised you about the data?
It was surprising to see the number of young people. A month or so ago, the message from various press outlets was that this virus was primarily a problem for people 65 years and older, and we’re discovering that this isn’t the only vulnerable population.

Why does obesity make COVID-19 worse?
We don’t have all the answers yet, but there are several factors to consider. One area we’re looking at is whether these patients have conditions often associated with obesity, such as high blood pressure, diabetes, or cardiovascular disease. But the fact that we’re seeing more young people with obesity get into trouble is puzzling, so it may also speak to a genetic component. That’s a speculation, but when you see otherwise healthy people get such severe disease, it makes you wonder whether there’s some sort of a genetic signature that puts certain patients at high risk.

Inflammation is another important factor. Obesity is a pro-inflammatory condition, and inflammation in the body changes the immune system. This could explain why obese patients who are otherwise healthy can contract a more serious coronavirus infection than others.

What’s happening with the immune system in these more serious cases?
Our immune systems are very complex, and hundreds of factors are involved — especially when the body is fighting an infection. With COVID-19, some patients’ immune systems go into overdrive, essentially going haywire. It’s a phenomenon referred to as a “cytokine storm,” an overproduction of activating compounds called cytokines, and it’s very, very deadly. Most of those patients have to be intubated, which further complicates things. So, it seems that the coronavirus is triggering the immune system in some people, and instead of being a beautifully concerted effort, it’s a complete storm and everything in the body goes out of control. For instance, of the 393 patients we studied, 15% were placed on dialysis due to declining kidney function even though they had no history of kidney disease, an example of how this immune activation can wreak havoc in the body and is very challenging to manage.

“What’s rather striking about the data we have compiled is that the obesity prevalence seems to be the greatest in people under the age of 65.”

— Dr. Monika Safford

How do these findings affect patient care?
They’re having a big impact on patient care; they’re helping us to identify which patients are likely to do the worst and need the closest monitoring. This, in turn, helps front-line healthcare workers make vital decisions.

We’ve also implemented a strategy to prone intubated patients, to put them on their stomachs, when necessary, because it changes the dynamics of the lungs, alleviating pressure and increasing blood flow. Reports in other countries have proved this to be very effective for obese patients. Most intensive care units in the U.S. have not routinely proned patients, but now with COVID-19, everyone is doing it because it makes a difference.

What are other research findings?
In terms of obesity, the findings are pretty consistent here in the United States. We’re continuing to closely watch data from countries like China, Korea, Spain, and Italy. However, none of those countries has the prevalence of obesity that the U.S. has. So, it remains to be seen whether we’re going to have a higher mortality rate in part because of our much higher prevalence of obesity.

Did this research have any limitations?
We were not able to include mortality rates and outcomes in this report because a lot of patients who are intubated remain on a ventilator for a long, long time. Three weeks is not uncommon. Many of the patients in our registry are still on ventilators, and we don’t know what their final outcomes will be.

Are there plans to expand this research?
Yes, absolutely. We’re continuing to add patients to the registry, which currently has over 4,000 patients, and we are in discussions with NewYork-Presbyterian/Columbia University Irving Medical Center on how to conduct analyses in collaboration with them. A large Columbia team, also with medical students doing the bulk of the chart abstraction work, is using the same instrument we are, which will facilitate collaborations.

We’re also finalizing another analysis to help physicians identify the most at-risk patients and make decisions accordingly, based on the data. Decisions such as who needs a continuous pulse oximeter, which measures oxygen and heart rate, can be guided by the patients who are likely to do the worst and need the closest monitoring.

What can we learn from these data?
That more research is needed. There’s a large group of physician investigators who are very interested in advancing knowledge for the rest of the country, so this is really just the beginning. More studies will be coming out in the near future.

The paper and full list of authors can be found here.

Monika M. Safford, M.D., chief of the Division of General Internal Medicine at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine, is a clinician-investigator known for her patient-centered research on diabetes, cardiovascular disease, and health disparities. Her more than 400 research articles have been published in medical journals including the Journal of the American Medical Association, Diabetes Care, Circulation, and the American Journal of Cardiology.

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