Severe forms of COVID-19 and higher death risk in patients with mild obesity

A trial involving almost 500 patients suggests considering a lower BMI cut-off value for assessing at-risk patients.

The risk of greater COVID-19 severity and death is higher even in people with mild obesity. This is according to a study published in the European Journal of Endocrinology and carried out by a research group of the University of Bologna.

The study findings showed that a Body Mass Index value (BMI) over 30 was associated with a significantly higher risk of respiratory failure, admission to intensive care and death in COVID-19 patients, regardless of age, gender and other associated diseases.

The BMI is a biometric value that is derived from the weight and height of a person. A BMI value between 30 and 35 identifies mild obesity. The current guidelines for identifying those at higher risk of developing acute forms of COVID-19 in the UK and US are set at a BMI of 40, which represents severe obesity. However, the results of this study suggest the BMI cut-off value for at-risk patients should be lower, thus including all types of obese patients.

Obesity and Covid-19

Since the onset of the COVID-19 pandemic, several studies have implicated obesity as a risk factor for more severe effects and death in Sars-COV-2 infection. However, the research carried out so far has been necessarily based on smaller studies and limited data, as it essentially aimed to draft guidelines for identifying categories of at-risk patients. 

The research group from the University of Bologna carried out this study drawing information from almost 500 patients that were hospitalised with COVID-19. Their data confirmed that obesity was associated with a significantly higher risk of severity and death, however, they also found out that this is true for mildly obese patients as well.

“Our study showed that any grade of obesity is associated with severe COVID-19 illness”, comments Matteo Rottoli, who led the research group and is himself a researcher at the University of Bologna. “Our results suggest that people with mild obesity should also be identified as a population at risk”.

Finding out why

Despite the strength of the link between higher BMI values and severe COVID-19 illness, its causes remain to be explained. There may be many answers as to what this link could be: an impaired immunological response to viral infections, alterations of lung function and obesity-related chronic inflammatory states. 

“Our next step will be to understand the mechanisms underlying this link”, says Rottoli. “Our hypothesis is that SARS-CoV-2 infection outcomes depend on the metabolic profile of patients, meaning that obesity, interlaced with diabetes and metabolic syndrome, has an impact too”.

While an answer to these questions has not been found yet, researchers recommend that people and health-care practitioners should be aware of the increased risk of COVID-19 illness with any grade of obesity. “BMI cut-off values should be reassessed to ensure we identify everyone at higher risk of serious infection”, says Rottoli. “We do not want to underestimate the potential population impact of SARS-CoV-2 infection, particularly in Western countries with higher obesity rates”.

The authors of the study

This study was published in the European Journal of Endocrinology with the title “How important is obesity as a risk factor for respiratory failure, intensive care admission and death in hospitalised COVID-19 patients?”.

It was carried out by a research group of the Department of Medicine and Surgery at the University of Bologna. The group members are: Matteo Rottoli, Paolo Bernante, Angela Belvedere, Francesca Balsamo, Silvia Garelli, Maddalena Giannella, Alessandra Cascavilla, Sara Tedeschi, Stefano Ianniruberto, Elena Rosselli Del Turco, Tommaso Tonetti, Vito Marco Ranieri, Gilberto Poggioli, Uberto Pagotto, Pierluigi Viale, Michele Bartoletti. The University of Ferrara also participated in the research.

Published on: 03 August 2020