Lung function levels influence link between obesity, COVID-19 risk
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In a new study, researchers found that obesity interacts with low underlying lung function and raises the risk for COVID-19, according to data published in the American Journal of Respiratory and Critical Care Medicine.
“Obesity is associated with immune suppression and may be associated with increased risk of COVID-19,” Dinh Bui, MPH, PhD, from the Allergy and Lung Health Unit at the Centre of Epidemiology and Biostatistics at the Melbourne School of Population and Global Health at the University of Melbourne, Australia, and colleagues wrote. “This association may be modified by factors such as lung function.”
Researchers evaluated the association between obesity and risk for COVID-19 among 36,896 participants (mean age, 69.3 years) in the UK Biobank Study who were tested for SARS-CoV-2 infection. They used baseline BMI to classify patients by normal weight (< 25 kg/m2), overweight (25-30 kg/m2) and obesity (> 30 kg/m2). Investigators categorized FEV1, FVC and their ratio at baseline.
In the cohort, 5,757 individuals (mean age, 65.3 years; 50% women) tested positive for COVID-19 infection. Of those, 42.3% had overweight and 29% had obesity.
Overweight (OR = 1.2; 95% CI, 1.12-1.3) and obesity (OR = 1.31; 95% CI, 1.21-1.42) were associated with increased risk for testing positive for SARS-CoV-2 infection. This risk was greatest among individuals with obesity compared with individuals with overweight (P = .017).
Among individuals with an FEV1 below the median (OR = 1.48; 95% CI, 1.29-1.71) and an FVC below the median (OR = 1.47; 95% CI, 1.28-1.69), the researchers reported a stronger association between obesity and a positive test compared with individuals with an FEV1 above the median (OR = 1.22; 95% CI, 1.07-1.38; P = .02) and an FVC above the median (OR = 1.28; 95% CI, 1.12-1.46; P = .02).
“Whilst both obesity and low lung function have been shown to increase risk of testing positive for SARS-CoV-2 independently, we observed that these two factors interact to multiplicatively increase risk of SARS-CoV-2 test positivity. Therefore, risk for SARS-CoV-2 test positivity was higher amongst obese individuals who also have low lung function compared to obese individuals with normal lung function,” the researchers wrote.
When evaluating obesity class 1 (< 35 kg/m2) and class 2 (> 35 kg/m2) individually, researchers observed similar associations for the risk for COVID-19 (OR = 1.31; 95% CI, 1.2-1.43 vs. OR = 1.3; 95% CI, 1.15-1.44). When researchers evaluated individuals with a BMI below 18.5 kg/m2, they found reduced risk for COVID-19 (OR = 0.53; 95% CI, 0.3-0.95).
“Our findings suggest that individuals with poor lung function, particularly the obese, should be encouraged to take extra precautions to reduce the risk of acquiring this disease,” the researchers wrote. “In the short term, this may include adhering strictly to mask and social distancing mandates and practicing good hand hygiene to mitigate risk as the pandemic continues.”