Studies affirm obesity is risk factor for severe COVID-19 outcomes
Two retrospective cohort studies published in Annals of Internal Medicine reinforce the notion that individuals with obesity are at greater risk for worse outcomes from COVID-19.
“Given the high prevalence of obesity, the potential effect of COVID-19 in the U.S. population is enormous,” Sara Y. Tartof, PhD, MPH, an infectious disease epidemiologist in the department of research and evaluation at Kaiser Permanente, and colleagues wrote in the first study.
Tartof and colleagues assessed almost 7,000 patients with a mean age 49.1 years and a mean BMI of 30.6 kg/m2. About half the cohort included women (55%) and Hispanic patients (54.2%), and the most prevalent comorbidities were hypertension (24%), hyperlipidemia (23%), diabetes (20%) and asthma (18%). All patients were treated at Kaiser Permanente’s Southern California network and diagnosed with COVID-19 between Feb. 13 and May 2.
The researchers found a J-shaped association between BMI and patients’ risk for death, even after adjusting for obesity-related comorbidities. Compared with patients with a BMI of 18.5 kg/m2 to 24 kg/m2, those with a BMI of 40 kg/m2 to 44 kg/m2 and greater than 45 kg/m2 had RRs of death of 2.68 (95% CI, 1.43–5.04) and 4.18 (95% CI, 2.12–8.26), respectively. The risk was “most striking” among those aged 60 years or younger and among men, Tartof and colleagues said.
In the second study, Michaela Restivo Anderson, MD, assistant professor of pulmonary critical care medicine at New York Presbyterian/Columbia University Medical Center, and colleagues analyzed data from 2,466 adults hospitalized with SARS-CoV-2 infection over a 45-day period at their institution.
The median age of the cohort was 67 years, 58% were men and 49% were Hispanic. Patients’ median BMI was 27.9 kg/m2, 52% of patients had hypertension, 40% had diabetes and the cohort had median number of two comorbid conditions.
Anderson and colleagues found that, compared with overweight patients, those with obesity had a higher risk for intubation or death, with the highest risk among those with a BMI of 40 kg/m2 or higher (HR = 1.6; 95% CI, 1.1–2.1). The link between obesity and worse outcomes was strongest among patients aged younger than 65 years (P for interaction by age = .042). BMI was not associated with admission levels of biomarkers of inflammation, cardiac injury or fibrinolysis, they said.
According to the researchers, BMI data were missing for 28% of the cohort.
“While we cannot say definitively that these missing values did not alter our results, I think there is strong evidence that our findings are robust,” Anderson told Healio Primary Care. “We performed multiple different statistical techniques to account for these missing values and identified similar results.”
Potential explanations for the higher risk
Tartof told Healio Primary Care that visceral adiposity might explain the association between obesity and severe COVID-19 outcomes, and why the connection is more pronounced in men than women.
“We know that at high BMI levels, men deposit fat differently than women, and have more of a damaging kind of fat called visceral fat,” she said. “Although the exact mechanism is unclear, visceral fat and COVID-19 share a common link in the upregulation of the proinflammatory, prothrombotic and vasoconstrictive hormone angiotensin II. We suspect that COVID-19 is able to accelerate injuries from this pathway among persons with severe obesity.”
Anderson noted that obesity affects the body in numerous ways.
“It could increase the risk of respiratory failure including greater inflammation, increased production of factors related to blood clot formation and by simply exerting pressure on the diaphragm and lungs,” she said.
Tartof urged physicians to tell their patients — regardless of BMI, sex or age — to keep practicing physical distancing.
“One thing we’ve learned through this pandemic is that COVID-19 morbidity and mortality can also be very unpredictable,” she said.
Anderson agreed, adding that no matter the risk factors, “everyone should continue to take additional safety precautions” to protect themselves against COVID-19.