Disease severity increased with BMI in retrospective analysis

Obesity was found to be a risk factor for Covid-19 severity in a newly published retrospective analysis involving coronavirus patients consecutively admitted to the ICU at a single hospital in France, with disease severity increasing with body mass index (BMI).

The need for mechanical ventilation was significantly associated with both higher BMI and male sex in multivariate logistic regression analysis, independent of age, diabetes and hypertension.

Covid-19 patients with BMIs greater than 35 kg/m2 had a more than 7-fold greater risk for invasive mechanical ventilation than patients with BMIs of less than 25 kg/m2 (odds ratio, 7.36, 95% CI, 1.63-33.14; P=0.02).

Researcher Arthur Simonnet of Central University Hospital, Lille, France, and colleagues wrote that a main finding was the unexpectedly high rate of obesity among patients admitted to the ICU with Covid-19.

Almost half (47.5%) of the SARS-CoV-2 patients consecutively admitted to the ICU had BMIs of 30 kg/m2 or greater, while 13.7% had BMIs of 35-39 kg/m2 and 14.5% had BMIs of 40 kg/m2 or greater.

Writing in the journal Obesity, the researchers noted that this BMI distribution was significantly higher than that seen in a group of control subjects admitted to the same ICU for severe acute pulmonary conditions in years prior to the novel coronavirus outbreak.

“Importantly, we also showed that the need for invasive mechanical ventilation, a robust proxy for the severity of SARS-CoV-2, gradually increased with body mass categories, reaching nearly 90% in patients with a BMI >35 kg/m2,” they wrote.

Simonnet and colleagues noted that while the chronic conditions diabetes, hypertension, cardiovascular disease, and chronic respiratory disease have all been identified as risk factors for more severe Covid-19 presentations, “surprisingly BMI was rarely mentioned among the significant clinical risk factors” in early clinical reports from China, Italy and the United States.

“Obesity has, however, been described as an independent predisposition factor for severe H1N1 pulmonary infection. Moreover, abdominal obesity is associated with impaired ventilation of the base of the lungs, resulting in reduced oxygen saturation of blood,” they wrote.

Abdominal obesity has also been shown to be associated with a chronic, low-grade inflammation which could impair immune response and negatively affect the lung parenchyma and bronchi, the researchers added.

“Altogether, it appears that obesity per se may be an independent risk factor for SARS-CoV-2,” they wrote.

To test this hypothesis, Simonnet and colleagues retrospectively analyzed BMI and outcomes among 124 consecutive patients with Covid-19 treated at their hospital during the study period.

At the time of analysis (April 6th), 60 patients (48%) had been discharged alive from intensive care, 18 (15%) had died and 46 remained hospitalized in intensive care. The patients were mostly males (73%), and their median (IQR) age was 60 (51-70) years.

Eighty-five of the 124 study participants (68.6%) required mechanical ventilation, including 62 at admission, 13 at day 1, 4 at day 2 and the remaining 6 within 7 days.

Their median (IQR) BMI was 31.1 (27.3-37.5) kg/m2 as compared as 27.0 (25.3 to 30.8) kg/m2 in the 39 (31.4%) patients who did not require mechanical ventilation (P<0.001).

The researchers noted that the distribution of BMI categories differed markedly between the two subgroups (P<0.01; Fisher exact test for trend); with obesity (BMI>30 kg/m2) and severe obesity (BMI≥35 kg/m2) being more frequent among patients who required mechanical ventilation than among those who did not: 56.4% versus 28.2% and 35.3% vs 12.8%, respectively.

An editorial published in Obesity Reviews offered another take on the possible association. Radwan Kassir, MD, PhD, of the Department of Bariatric Surgery CHU Felix Guyon, in Reunion, France, wrote that while there is not yet much research on the impact of BMI on Covid-19 risk and outcomes, “the role of obesity in the Covid-19 epidemic must not be ignored.”

“By analogy to other respiratory infections, obesity may play an important role in Covid-19 transmission,” Kassir wrote, noting that obesity has been shown to increase the duration of virus shedding in influenza A and it has also been shown to be an independent risk factor for hospitalization and death in patients with H1N1 influenza.

Kassir noted that levels of angiotensin converting enzyme (ACE-2) have been shown to be higher in adipose tissue than in lung tissue. ACE-2 is believed to be the receptor for entry of Covid-19 into host cells.

In addition, Kassir wrote, adipose tissue can serve as a reservoir for a host of human viruses, including HIV, influenza A and Mycobacterium tuberculosis.

“By analogy, Covid-19 might also infect adipose tissue and then spread to other organs.”

“Thus, we recommend extra attention and precautions for patients with obesity during this epidemic,” Kassir concluded. “Whenever Covid-19 infection is suspected, screening must be systematic, particularly if the patient has obesity. Adipose tissue can be a research model to help understand the pathogenesis of Covid-19 infection and develop an effective treatment.”

  1. Obesity was found to be a risk factor for Covid-19 severity in patients consecutively admitted to the ICU at a single hospital in France, with disease severity increasing with body mass index (BMI).

  2. Covid-19 patients with BMIs of 35 kg/m2 had a more than 7-fold greater risk for invasive mechanical ventilation than patients with BMIs of less than 25 kg/m2 (odds ratio, 7.36, 95% CI, 1.63-33.14; P=0.02).

Salynn Boyles, Contributing Writer, BreakingMED™

Funding for this study was provided by the European Commission, the European Genomic Institute for Diabetes and others.

The researchers declared no relevant conflicts of interest related to this study.

Cat ID: 125

Topic ID: 79,125,254,930,287,500,503,728,932,574,730,933,125,190,469,520,926,192,927,151,928,925,934