Study finds severe obesity raises risk of COVID-19 death

Over the past year, many scientific teams around the world have reported that obese people who contract the coronavirus are especially likely to become dangerously ill.

Now, a large new study, of nearly 150,000 adults at more than 200 hospitals across the United States, p aints a more detailed picture of the connection between weight and COVID19 outcomes.

The study, performed by a team of researchers at the Centers for Disease Control and Prevention, has confirmed that obesity significantly increases the risk for hospitalization and death among those who contract the virus. And among those who are obese, the risk increases as a patient’s body mass index, or BMI, a ratio of weight to height, increases. Patients with a BMI of 45 or higher, which corresponds to severe obesity, were 33% more likely to be hospitalized and 61% more likely to die than those who were at a healthy weight, the researchers found.

“The findings of the study highlight the serious clinical public health implications of elevated BMI, and they suggest the continued need for intensive management of COVID-19 illness, especially among patients affected by severe obesity,” said the lead author, Lyudmyla Kompaniyets, a health economist at the Division of Nutrition, Physical Activity and Obesity at the CDC.

But the relations h ip between weight and outcomes is nuanced. COVID19 patients who were underweight were also more likely to be hospitalized than those who were at a healthy weight, although they were not more likely to be admitted to the intensive care unit or to die.

Kompaniyets and her colleagues used a database of COVID-19 cases to identify 148,494 adults who received a diagnosis of the disease at American hospitals from last March to December. They calculated the BMI of each patient and looked for correlations between BMI and a variety of serious outcomes, including hospitalization, ICU admission, mechanical ventilation and death.

They found that obesity, which is defined as a BMI of 30 or higher, increased the risk of both hospitalization and death. Patients with a BMI of 30 to 34.9 were just 7% more likely to be hospitalized and 8% more likely to die than people who were at a healthy weight, but the risks increased sharply as BMI rose.

Providing evidence for this kind of “dose response” relationship makes the study particularly compelling, said Dr. Anne Dixon, director of pulmonary and critical care medicine at the University of Vermont Medical Center, who was not involved in the research. “What it shows is the more severe your obesity, the worse the effect is. And the fact that goes up stepwise with increasing levels of obesity, I think, adds sort of biological plausibility to the relationship between obesity and the outcome.”

The connection between obesity and poor outcomes was strongest among patients under 65, but it held even for older adults. Previous, smaller studies have not found strong links between obesity a nd severity of COVID-19 in older adults.