An unprecedented study links the risk of severe covid to obese people of all degrees

People with any degree of obesity, even mild, are at least 32% more likely to die with covid-19 than a non-obese person. The result is contained in an unprecedented study published by Brazilian researchers from the CoVida Network in the English journal BMJ (British Medical Journal), evaluating 21 thousand hospitalizations of people aged 20 and over in Brazil until June 9, 2020.

To arrive at the numbers, the research evaluated the records of 8,848 adults and 12,945 elderly people in Sivep-Influenza (Influenza Surveillance Information System), of the Ministry of Health, which notifies cases and deaths of SARS (Severe Acute Respiratory Syndrome) and covid -19. All selected inpatients had a positive RT-PCR test.

“In the analyzes by degree of obesity, we did not observe much difference in the prevalence of adverse outcomes, except for the prevalence of death, which increased with the severity of obesity”, says the article, the first published describing —in large-scale analysis— the relationship between obesity and covid-19 in Brazil.

The WHO (World Health Organization) classifies obesity into three levels, defined by the BMI (body mass index):

  • non-obese – < 30
  • Grade 1 obesity 30 to 34.9
  • Grade 2 obesity 35 to 39.9
  • Grade 3 (or morbid) obesity 40

To find your BMI, just do a simple math: divide the weight (in kg) by the squared height (in meters).

In all degrees, according to the study, there were more deaths among obese adults than in the general public, growing according to the BMI range:

  • Grade 1 obesity – 32% (more deaths than non-obese)
  • Grade 2 obesity – 41%
  • Grade 3 obesity – 77%

“Although it is known that BMI does not distinguish between fat and lean mass and therefore can lead to misclassification bias, BMI has been shown to be a strong predictor of excess body fat and has been widely used in epidemiological studies,” highlights the article.

For the researchers, the result can help guide the PNI (National Immunization Plan), which currently provides as a priority group only people with grade 3 obesity.

“With this evidence, it is expected that all people with obesity, regardless of severity, age and existence of other comorbidities, are included in the priority group for vaccine against covid-19”, says Natanael de Jesus Silva, one of the authors of the study.

More deaths among seniors

According to the study, taking into account age, the death of obese adults was 33% higher than non-obese ones. Among the elderly, this prevalence is even higher, reaching 67%.

“Obesity by itself seemed to pose a greater risk of serious outcomes, especially death, in the elderly,” the article adds.

According to Aline Rocha, a doctoral student in nutrition and one of the researchers who signed the article, the result of the study was already expected from what was seen in practice.

“We didn’t know how to measure how much, but we knew and expected obesity to have a higher number of death outcomes — and that’s what happened. And the more obese, the greater this prevalence, alone or combined with other comorbidities,” he explains .

If associated with other comorbidities, the numbers get even worse. For example: in the case of obese adults with diabetes or cardiovascular disease, the survey found a prevalence of invasive mechanical ventilation 3.76 times higher than among non-obese patients; and death, 1.79 times higher.

When we have another risk factor associated with obesity, this patient becomes a kind of risk ‘bomb’. For example: diabetes is bad enough; but when you have diabetes and obesity it is even worse.

According to the latest bulletin from the Ministry of Health, published on August 20, obesity was identified as a comorbidity associated with 41,000 deaths of covid-19 since March 2020, with a greater absolute number among adults than the elderly.

Bulletin of August 20, Ministry of Health, shows more deaths of obese adults than elderly - Reproduction/Ministry of Health Bulletin - Reproduction/Ministry of Health Bulletin

Bulletin of August 20, Ministry of Health, shows more deaths of obese adults than elderly

Image: Reproduction/Ministry of Health Bulletin

One of the factors that helps to understand this result is that there are many more young obese people than old people, due to the lower life expectancy of those who are obese. In the study, for example, among the 21 thousand cases analyzed, the prevalence of obese patients among hospitalized adults was 9.7%; among the elderly, this percentage drops to 3.5%.

“This is from the physiology of the elderly themselves. The older they are, the greater the chance of being malnourished. Therefore, the higher percentage of obese adults”, explains Aline.

Problems linked to obesity

Also in the article, researchers try to explain the relationship between obesity and covid worsening. For them, increased weight can cause decompensated blood glucose and can reduce the elasticity of the chest—conditions that make breathing difficult.

They also claim that obesity is associated with sleep apnea and obstructive lung disease — which impede the proper functioning of ventilation mechanisms.

Another point is the compromised immune response, which makes the individual more vulnerable to infections and less responsive to antiviral drugs.

For Aline Rocha, the result of the research should serve as a warning about the risks of obesity.

“It reinforces the importance of the issue of preventing obesity in general, and not just for the covid. We know that it is associated with other chronic diseases: those who are obese have a greater chance of having diabetes, hypertension, cardiovascular diseases. And we saw how this combination greatly aggravated the cases of covid. Brazil is experiencing an epidemic of obesity and this is worrying,” he concludes.