Over the past year, many scientific teams around the world have reported that obese people who contract the coronavirus are likely to become dangerously ill.
Now, a large new study, of nearly 150,000 adults in more than 200 hospitals across the United States, paints a more detailed picture of the relationship between weight and Covid-19 outcomes.
The study, conducted by a team of researchers at the Centers for Disease Control and Prevention, confirmed that obesity significantly increases the risk of hospitalization and death for those who contract the virus. And among those who are overweight, the risk increases as the patient’s body mass index, or BMI, a ratio of weight to height increases. Patients found that patients with a BMI of 45 or higher, consistent with severe obesity, were admitted 33 percent more to the hospital and 61 percent more likely to die than those with a healthy weight.
“The findings of the study highlight the serious clinical implications for public health of increased BMI, and suggest that the need for intensive management of Covid-19 diseases continues, especially among patients affected by severe obesity,” the lead author said. , Lyudmyla Kompaniyets, a Health Economist at the Division of Nutrition, Physical Activity and Obesity at the CDC
But the relationship between weight and outcomes is nuanced. Covid-19 patients who were underweight were also more likely to be admitted to the hospital than those who had a healthy weight, although they were no longer likely to be admitted to the intensive care unit or to die.
Dr. Kompaniyets and her colleagues used a database of Covid-19 cases to identify 148,494 adults who received a diagnosis of the disease in U.S. 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, defined as a BMI of 30 or higher, increased the risk of hospitalization as well as death. Patients with a BMI of 30 to 34.9 were only 7 percent more likely to be hospitalized and 8 percent more likely to die than people with a healthy weight, but the risks increased sharply as the BMI increased. has.
The evidence of this kind of ‘dose-response’ ratio makes the study particularly convincing, says Dr. Anne Dixon, the director of medical and pulmonary medicine at the University of Vermont, who was not involved in the research. ‘What it shows is the worse your obesity, the worse the effect. And the fact that step by step with increasing levels of obesity, I think, contributes a kind of biological credibility to the link between obesity and the outcome. “
The link between obesity and poor outcomes was strongest among patients under 65, but it was even for older adults. Previous, smaller studies have not found strong links between obesity and severity of Covid-19 in older adults.
“Perhaps because they have more power from this large sample size, they have shown that obesity remains an important risk factor for death in older adults as well,” said Dr. Michaela R. Anderson, an expert in medicine for lung and critical care at Columbia University Medical Center, which was not involved in the study. “This is a beautifully conducted study with a large population.”
Dr. Kompaniyets and her colleagues also documented a linear relationship between BMI and the likelihood of mechanical ventilation; the higher the BMI, the greater the chance that a patient will require such intervention, which is invasive and can lead to serious complications.
The study also found that underweight patients, with a BMI below 18.5, were 20 percent more likely to be admitted to the hospital than those who had a healthy weight. The reasons are not entirely clear, but may stem from the fact that some of these patients were malnourished or debilitated or had other diseases.
The BMI range associated with the best results, the researchers found, was close to the dividing line between what is considered healthy and overweight, consistent with previous research suggesting that a few extra pounds can help protect people if they contract an infectious disease.
“Exactly why the association exists is currently unknown,” said Dr. Alyson Goodman, a pediatrician and medical epidemiologist at the CDC, and co-author of the study said. One possibility is that the fact that a little extra fat is a much needed energy reserve in a long illness.
The findings highlight the importance of providing care to patients with severe obesity and to ensuring that obese people have access to vaccines and other preventative measures.
“This only provides further evidence for the recommendation to vaccinate those with high BMI as early as possible,” said Sara Y. Tartof, an epidemiologist of infectious diseases at the Department of Research and Evaluation at Kaiser Permanente. was not involved in the study. .