Is obesity a top risk factor in COVID-19 hospitalizations?

Florida Gov. Ron DeSantis plans to form a task force to look at reopening schools and businesses including gyms.

DeSantis said he understands why there were recommendations to close gyms due to the spread of germs. But he expressed concern that people may not be getting enough physical activity amid the shutdowns.

"The No. 1 group of people who have been susceptible to COVID-19 if you look in New York and some of these other (places), obesity is, like, the No. 1 factor in whether you really get hit hard by COVID-19," he said at his April 14 press briefing.

Overwhelming research shows age as the leading risk factor in the severity of the disease, however early research also shows that obesity is a risk factor in hospitalizations for COVID-19. 

That’s a cause for concern in the United States, where 40% of the population is obese. Scientists have called attention to the research about obesity and COVID-19 because it’s another sign that age is not the only factor.

We found a few studies that examine the role of obesity in COVID-19. These studies come with limitations, including that they were usually limited to a certain geographic region and may not include complete information on patients, such as outcomes after the study period. But they do provide a useful look at what we know so far about obesity and COVID-19. The studies we saw from New York were not yet peer-reviewed.

Researchers at NYU Langone Health in New York City conducted two studies about obesity and COVID-19, among the largest examinations of COVID-19 patients to date. Most of the patients in the two studies overlap. The studies appear in the journal Clinical Infectious Diseases and on the pre-publication website medRxiv. 

One study, led by Dr. Christopher Petrilli, examined the factors associated with hospitalization and critical illness among 4,103 patients with COVID-19 for about one month. Nearly half of the patients were hospitalized. The study found that the strongest hospitalization risks were age over 75, obesity and history of heart failure, in that order.

"Age is the most important demographic factor for severity of disease and more important than any single disease, but obesity is among the most important diseases in terms of risk," Dr. Leora Horwitz, one of the authors, told PolitiFact.

Researchers defined obese as a body-mass index of greater than 30. BMI is a measure of body fat based on a person’s height and weight. Normal weight is a BMI of 18.5 to 24.9.

Among the 1,999 hospitalized patients, 33% had a BMI of 30-40 while about 7% had a BMI of more than 40. The rates were similar among those who faced critical illness — as defined by intensive care, mechanical ventilation, hospice and/or death.

"The chronic condition with the strongest association with critical illness was obesity, with a substantially higher odds ratio than any cardiovascular or pulmonary disease," researchers wrote.

Obesity tends to increase risk for other conditions such as diabetes and heart disease, which are also risk factors for severe disease with COVID-19. 

"Separately, it does seem that the severe cases of COVID-19 have a strong component of inflammation — the body reacting (or overreacting) to the infection to cause severe irritation to the lungs," Horwitz told PolitiFact. "It turns out that obesity itself actually increases the amount of inflammation in the body. So it's possible that obesity also directly contributes to worse outcomes in that way."

The other study by NYU Langone examined BMI stratified by age in COVID-19-positive symptomatic patients at the hospital. Researchers found that COVID-19 infected patients under age 60 with a BMI of 30-34 were twice as likely to be admitted to acute or critical care as those  at same age with BMIs less than 30. Those who were morbidly obese, defined as having a BMI greater than 35, were three times as likely be admitted to the ICU. 

"Though patients aged <60 years are generally considered a lower risk group of COVID-19 disease severity, based on data from our institution, obesity appears to be a previously unrecognized risk factor for hospital admission and need for critical care," researchers wrote. 

In the study, 37% of patients who came to the emergency department had BMI greater than 30. In New York City overall, 22% have a BMI greater than 30, so more people are showing up in the emergency department who are obese, author Dr. Jennifer Lighter told PolitiFact.

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A spokeswoman for DeSantis cited a news article in USA Today about a study by the U.S. Centers for Disease Control and Prevention which examined characteristics of hospitalized COVID-19 patients in 14 states in March.

The CDC found that among 178 adult patients with data on underlying conditions as of March 30, the vast majority had one or more underlying conditions. The most common underlying conditions in order were hypertension closely followed by obesity. (The other conditions that followed were chronic lung disease, diabetes mellitus and cardiovascular disease.)

A DeSantis spokeswoman also pointed to an article by Reuters about New Orleans’ death rate from COVID-19. Reuters reported that obesity was seen in 25% of the COVID-19 deaths in Louisiana, according to the state health department. 

A paper about obesity in COVID-19 cases at a hospital in Shenzhen, China found that patients with obesity are at increased risk of complications from viral respiratory infections however, the association with severity of COVID- 19 was unclear. Researchers found that obesity, especially in men, significantly increases the risk of developing severe pneumonia in COVID-19 patients. 

The study examined 383 patients admitted in January and February.

We sent the NYU research findings to a few doctors who were not involved in the studies to ask if research so far shows obesity is the No. 1 factor in COVID-19 critical cases or hospitalization cases. 

"Not exactly," said Dr. Angela Fitch, associate director MassGeneral Weight Center. "This data shows that in people less than 60 years old, having the disease of obesity increased the need for admission to the hospital and admission to the ICU. Age is still the No. 1 factor so far but in those patients who are younger, obesity is a risk factor for more severe disease."

The early data across many countries show a link between severity of disease and obesity, said Fitch, vice president of the Obesity Medicine Association. However, further research is needed nationwide and across the world, she said. 

DeSantis said "obesity is, like, the No. 1 factor in whether you really get hit hard by COVID-19."

DeSantis didn’t explain what he meant by "hit hard," so we looked at research about COVID-19 patients who were hospitalized. We did not find any study that showed that obesity is the No. 1 risk factor. Most research and evidence so far shows age as the top factor. But early research suggests that obesity is also a key risk factor. 

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