Patients with severe obesity (i.e. a BMI of ≥40) had more than double the risk of mechanical ventilation and a 26% higher mortality compared with normal-weight COVID-19 patients in the AHA COVID-19 Cardiovascular Disease (CVD) Registry. The mortality association was strongest in younger adults: patients aged ≤50 years with severe obesity had a 36% higher risk of death compared with their normal-weight peers .
The BMI analysis from the AHA COVID-19 CVD Registry was presented by Dr Nicholas Hendren (University of Texas Southwestern, USA). The study’s hypothesis was that obesity is associated with worse outcomes in COVID-19, especially in younger patients. The primary outcome was a composite of in-hospital death or mechanical ventilation, as well as the individual components of in-hospital death and mechanical ventilation. Secondary endpoints included major adverse cardiovascular events (MACE), venous thromboembolism, and renal replacement therapy.
BMI data was available for 7,606 patients. Mean BMI in this cohort was higher than that in the US National Health and Nutrition Examination Survey (NHANES), especially among patients aged ≤50 years. In this sample, 194 patients were underweight (BMI <18.5 kg/m2), 1,793 had a normal weight (BMI 18.5–24.9 kg/m2), 2,308 had overweight (BMI 25–29.5 kg/m2), 1,623 had class I obesity (BMI 30–34.9 kg/m2), 846 had class II obesity (BMI 35–39.5 kg/m2), and 842 had class III obesity (BMI ≥40 kg/m2). Obesity was associated with an elevated risk for the primary endpoint compared with normal weight. The risk increased with worse degrees of obesity:
- class I obesity: OR 1.28 (95% CI 1.09–1.51);
- class II obesity: OR 1.57 (95% CI 1.29–1.91);
- class III obesity: OR 1.80 (95% CI 1.47–2.20).
Dr Hendren noted that the differences were mainly driven by the risk of mechanical ventilation, which was significantly higher in overweight and obese patients than in patients with normal weight.
No association was seen between obesity class and risk of MACE (i.e. all-cause death, in-hospital stroke, heart failure, or myocardial infarction). Only class II obesity was associated with a higher risk of venous thromboembolism. Obesity classes I, II, and III were associated with a stepwise increase in the risk of in-hospital initiation of renal replacement therapy. Class III obesity was associated with elevated risk of in-hospital mortality only in patients aged ≤50 years (HR 1.36; 95% CI 1.01–1.84). The risks of poor outcomes related to obesity were most pronounced in patients aged ≤50 years (P for interaction <0.05 for all primary endpoints).
“We believe that clear public health messaging is needed for younger obese individuals who may underestimate their risk if they get COVID-19,” Dr Hendren concluded. “Severely obese individuals should be considered at high risk for severe COVID-19 disease and may warrant prioritisation for a COVID-19 vaccine.”
- Hendren N, et al. Association of Body Mass Index with Death, Mechanical Ventilation, and Cardiovascular Outcomes in COVID-19: Findings from the AHA COVID-19 Cardiovascular Disease Registry. LBS.08, AHA Scientific Sessions 2020, 13–17 Nov.
- Hendren N, et al. Circulation. 2021;143:135–144.
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