And in the other US study, Christopher M. Petrilli, MD, NYU Grossman School of Medicine, and colleagues looked at 4103 patients with COVID-19 treated between March 1 and April 2, 2020, and followed to April 7.
Just under half of patients (48.7%) were hospitalized, of whom 22.3% required mechanical ventilation and 14.6% died or were discharged to hospice. The research was posted April 11 on medRxiv.
It showed that, apart from age, the strongest predictors of hospitalization were BMI > 40 kg/m2 (OR, 6.2) and heart failure (OR, 4.3).
“It is notable that the chronic condition with the strongest association with critical illness was obesity, with a substantially higher odds ratio than any cardiovascular or pulmonary disease,” they note.
Is Inflammation the Culprit?
Pattou believes that the culprit behind the increased risk of disease severity seen with obesity in COVID-19 is inflammation, mediated by fibrin deposits in the circulation, which his colleagues have seen on autopsy, and which “block oxygen passage through the blood.”
This may help explain why mechanical ventilation can be less successful in these patients.
“The answer is to get rid of this inflammation,” Pattou observed.
Petrilli and colleagues also observe that obesity “is well-recognized to be a proinflammatory condition.”
And their findings show “the importance of inflammatory markers in distinguishing future critical from noncritical illness,” they say, noting that, among these markers, early elevations in C-reactive protein and D-dimer “had the strongest association with mechanical ventilation or mortality.”
Livio Luzi, MD, of IRCCS MultiMedica, Milan, Italy, has previously written on the relationship between influenza and obesity, and discussed with Medscape Medical News the potential lessons for the COVID-19 pandemic.
“Obesity is characterized by an impairment of immune response and by a low-grade chronic inflammation. Furthermore, obese subjects have an altered dynamic of pulmonary ventilation, with reduced diaphragmatic excursion,” Luzi said.
These factors, alongside others, “may help to explain” the current results, and stress the importance of close monitoring of those with obesity and COVID-19, he concluded.