In a large international study of patients admitted to the ICU with COVID-19, the likelihood of having severe pneumonia (i.e., needing invasive mechanical ventilation) increased stepwise with increasing body mass index (BMI) – independent of diabetes, hypertension, dyslipidemia, or current smoking.
The main finding was a linear correlation between BMI and need for invasive mechanical ventilation, after adjustment for center, age, sex, and other prespecified metabolic risk factors.
Risk was “highest for older people and males, but the next most important risk factor to developing severe pneumonia if infected [was] obesity,” said François Pattou, MD, Centre Hospitalier Universitaire de Lille (France), who presented the findings at the ObesityWeek 2020 virtual meeting. The results were also recently published in a preprint article in The Lancet.
Dr. Pattou and colleagues first reported back in April that obesity is one of the biggest risk factors for severe COVID-19 infection, especially in younger patients. Many further reports linked the two, and the French researchers then set out to conduct the current large, international, multicenter cohort study.
“The high number of patients included here [allowed us] to disentangle the role of various metabolic cofactors and to show that obesity, not diabetes or hypertension, was the main determinant of severe pneumonia [after age and gender],” Dr. Pattou said in an interview.
And the impact of obesity was most pronounced in women younger than 50 years.
Patients with severe obesity must protect themselves
Of interest, the study also found an “obesity paradox” for mortality after admission to the ICU.
Specifically, compared with leaner patients (BMI < 25 kg/m2), those with severe obesity (obesity class III, BMI ≥ 40) had an increased risk of dying within 28 days of admission to ICU. But patients with overweight to moderate obesity (BMI 25-39.9) had a lower risk of this outcome.
“The second original finding of our study,” Dr. Pattou continued, was the “nonlinear relation observed between BMI and all-cause mortality rate in ICU patients.”
Matteo Rottoli, MD, PhD, author of a related study reported by in July, said the new trial “confirms the findings of our study, which are that obesity is an independent risk factor for intensive care admission and death.”
Dr. Rottoli, from Alma Mater Studiorum, University of Bologna, Italy, and colleagues found that in their population of patients with COVID-19, a BMI > 35 was associated with a greater risk of death.
The takeaway message from the research is that “obesity should be considered one of the most important parameters to identify the population at risk” of getting COVID-19 who need to take extra precautions such as social distancing, Dr. Rottoli stressed.
Dr. Pattou agrees, particularly when it comes to severe obesity.
Intensive care physicians have learned a lot in the past months about COVID-19 pneumonia and how to address it (such as not precipitating intubation, using corticosteroids), he explained.
“Importantly, the general population has also learned a lot, and we can hope that patients with obesity, especially those with severe obesity, will take extra measures to protect themselves, resulting in a decrease of the incidence of severe pneumonia in young and severely obese patients,” he added.