Obese people aged 50 years and younger are more likely to be hospitalised with coronavirus disease 2019 (COVID-19) and are at higher risk of in-hospital death or mechanical ventilation, according to a study published in Circulation.
For the study, Nicholas S Hendren, MD, University of Texas Southwestern Medical Center, Dallas, Texas, and colleagues analysed data from patients hospitalised with COVID-19 at 88 US hospitals enrolled in the American Heart Association’s COVID-19 Cardiovascular Disease Registry, with data collection through July 22, 2020. The proportions of each BMI category in the registry were: underweight (3%), normal weight (24%), overweight (30%), class I obesity (21%), class II obesity (11%), and class III obesity (11%). Class II and III obese patients in the registry were approximately 16 and 18 years younger, respectively, than those with normal weight. Conversely, patients in the lower BMI classes had a higher prevalence of chronic kidney disease, current hemodialysis, and cardiovascular disease (P-trend <0.001 for all). There were no differences in the prevalence of hypertension or prior venous thromboembolism (VTE) by obesity class.
Among 7,606 patients (median age, 63 years; 55% males), in-hospital death or mechanical ventilation occurred in 2,109 (27.7%), in-hospital death occurred in 1,302 (17.1%), and mechanical ventilation occurred in 1,602 (21.1%) patients.
After multivariable adjustment, classes I to III obesity were associated with higher risks of in-hospital death or mechanical ventilation (odds ratio [OR], 1.28 [95% confidence interval (CI), 1.09–1.51], 1.57 [1.29–1.91], 1.80 [1.47–2.20], respectively), while class III obesity was associated with a higher risk of in-hospital death (hazard ratio [HR], 1.26 [95% CI, 1.00–1.58]). On the other hand, overweight and class I to III obese individuals were at higher risk for mechanical ventilation (OR, 1.28 [95% CI, 1.09–1.51], 1.54 [1.29–1.84], 1.88 [1.52–2.32], and 2.08 [1.68–2.58], respectively).
Moreover, BMI ≥40 was associated with a significantly greater odds of death or mechanical ventilation in those ≤50 years old (OR, 1.64 [95% CI, 1.23–2.21]), and a moderately increased risk in those 51 to 70 years old (OR, 1.40 [1.10–1.80]), but no significant increase in risk for those >70 years old (OR, 1.28 [0.83–1.95]). The absolute risk for death or mechanical ventilation among patients ≤50 years old with class III obesity was 23.1% in comparison with 12.5% for individuals who had normal weight. In addition, BMI ≥40 was associated with a significantly increased risk of in-hospital death in those ≤50 years old (HR, 1.36 [1.01–1.84]), but not those 51 to 70 years old (HR, 1.10 [0.82–1.46]) or >70 years old (HR, 1.16 [0.79–1.73]). The crude mortality rate for patients with age ≤50 and BMI ≥40 was 8.3%, compared to 3.3% and 5.0% for class I and II obesity (P-trend <0.05).
Further, in adjusted analyses, higher BMI was associated with dialysis initiation and with VTE but not with major adverse cardiac events.
“Our findings have important clinical and public health implications,” the authors wrote. “Although the severity of COVID-19 and probability of hospitalization and death are, in general, manyfold lower in younger than in older individuals, our findings confirm that the protection from younger age does not extend to class III obese individuals.“
“These observations support clear public health messaging and rigorous adherence to COVID-19 prevention strategies in obese individuals of all ages,” the authors noted, adding that severely obese individuals should be considered high risk for severe COVID-19 infection and may warrant prioritization for a COVID-19 vaccine.