Obesity portends worse outcomes in COVID-19, even for young adults

Obesity, particularly the severe class, was associated with an increased risk of mechanical ventilation and death in patients hospitalized with COVID-19 — a risk that is even more profound among the younger age group, reveals data from the AHA COVID-19 CVD registry*. 

“Although the severity of COVID-19 and probability of hospitalization and death are generally many-fold lower in younger compared with older individuals, our findings confirm that the protection from younger age does not extend to class III obese individuals,” the researchers stated.

“Clear public health messaging is needed for younger obese individuals who may underestimate their risk of severe COVID-19,” said presenting author Dr Nicholas Hendren from the University of Texas Southwestern Medical Center in Dallas, Texas, US, during the AHA 2020 Scientific Sessions.

Among the 7,606 hospitalized COVID-19 patients with BMI data available, obesity — particularly class III obesity (≥40.0 kg/m²) — was over-represented in the registry in comparison to the general US population, indicating that severely obese people were more likely to be hospitalised with COVID-19. Notably, this was especially so among younger individuals aged ≤50 years. [Circulation 2020;doi:10.1161/CIRCULATIONAHA.120.051936]

Compared with patients of normal weight (18.5-24.9 kg/m²), those who were obese were significantly more likely to experience the composite primary outcome of in-hospital mechanical ventilation and/or death — with greater risk seen with increasing obesity severity (adjusted odds ratios [ORs], 1.28, 1.57, and 1.80 for class I, II, and III obesity, respectively).

Specifically, the association was driven by the component of mechanical ventilation, which occurred at significantly higher rates in patients who were overweight or obese (≥25 kg/m²) than those with normal weight, regardless of age.

The risk of death was also significantly greater in those with severe obesity (class III; adjusted hazard ratio, 1.26, 95 percent confidence interval [CI], 1.00–1.58), but not in those with lower class of obesity.

When stratified by age group, the researchers found a significant interaction between age and BMI, such that the association between obesity and the primary composite outcome or death was particularly prominent in the younger subgroup (aged ≤50 years).

In addition, obesity was also associated with a higher risk of venous thromboembolism and renal replacement therapy. There was, however, no association between obesity and major adverse cardiovascular events (MACE).

“The similar in-hospital rates of cardiac arrest, shock, and MACE, despite the much younger age of obese patients hospitalized with COVID-19, highlights that young age does not protect against the cardiovascular complications of obesity,” the researchers pointed out.

“These observations support clear public health messaging and rigorous adherence to COVID-19 prevention strategies in obese individuals of all ages,” Hendren highlighted. “Severely obese individuals (BMI ≥40 kg/m²) should be considered high risk for severe COVID-19 infection and may warrant prioritization for a COVID-19 vaccine.”

*American Heart Association’s COVID-19 cardiovascular disease registry