Untangling BMI from other metabolic risk factors
Dr. Pattou said that, from Dec. 16, 2019, to Nov. 1, 2020, more than 45 million people worldwide tested positive for COVID-19 and more than 1.2 million people died from it.
Multiple studies have reported that, among people with COVID-19, those with obesity are at higher risk of hospitalization, ICU admission, invasive ventilation, and death, but it had not been clear if BMI was an independent risk factor.
Dr. Pattou and colleagues aimed to examine the relationship between BMI and COVID-19 pneumonia severity, defined by the need for mechanical ventilation (primary outcome), as well as 28-day all-cause mortality (secondary outcome) among patients admitted to the ICU.
They also sought to disentangle the effect of BMI from other metabolic risk factors (diabetes, hypertension, dyslipidemia, and current smoking) and examine the influence of age and sex on outcomes.
They performed a retrospective analysis of 1,461 patients with confirmed COVID-19 (positive reverse polymerase chain reaction test using a nasal or pharyngeal swab specimen) who were admitted to the ICU at 21 centers from Feb. 19 to May 11, 2020.
Participating centers were in France (13), Italy (3), the United States (1 in New York and 1 in Providence, R.I.), Israel (1), Belgium (1), and Spain (1).
Close to three-quarters of patients were men (73%), which is similar to multiple other studies, Dr. Pattou said. Patients were a mean age of 64 years and had a mean BMI of 28.1.
Half of patients had hypertension (52%), 29% had diabetes, 29% had hyperlipidemia, and 6.5% were current smokers.
Close to three-quarters (74%) required invasive mechanical ventilation, and 36% died within 28 days of ICU admission.
Each 5-kg/m2 increase in BMI was associated with a 27% increased risk of mechanical ventilation in the overall cohort and a 65% increased risk of this outcome among women younger than 50 years, after adjustment for other risk factors.
Male sex and each 10-year increase in age were associated with an 82% and a 17% increased risk of ventilation, respectively, but hypertension, diabetes, hyperlipidemia, and current smoking were not associated with a greater risk. After adjustment for center, age, sex, and prespecified metabolic risk factors, obesity class III (BMI ≥ 40) was associated with a 68% increase in mortality, compared with the risk seen in lean patients.
The findings were similar across different centers.
“To our knowledge, this study represents the first international collaborative effort to explore the association of BMI with the outcomes of pneumonia among COVID-19 patients admitted to ICU,” said the investigators.
They conclude that “available evidence should foster more focused and effective interventions in COVID-19 patients with the highest risk of severe pneumonia, in order to reduce future strain on intensive care resources worldwide, and inform physio-pathological research to elucidate the mechanism of severe lung damage in COVID-19.”
The study did not receive specific funding. The authors have reported no relevant financial relationships.
A version of this article originally appeared on.