- Among patients with COVID-19, obesity is emerging as a risk factor for hospitalization and the need for intensive care, including mechanical ventilation
- Retrospective studies have not adjusted these data for race/ethnicity, and analyses of the effects of race/ethnicity on COVID-19 outcomes have not adjusted for differences in obesity rates
- Some factors that might explain disparities in COVID-19 outcomes are vitamin D deficiency, inflammation associated with obesity and higher rates and poorer control of comorbidities, which are not fully considered in studies linking obesity with COVID-19
- The degree to which obesity and race/ethnicity are additive or multiplicative, mediators or confounders, has substantial implications for the medical and public health response to COVID-19
Obesity is emerging as a risk factor for severe COVID-19. Initial retrospective studies have demonstrated that rates of hospitalization and the need for intensive care, including mechanical ventilation, are higher for patients with obesity. These data have not been adjusted for race/ethnicity, and analyses of the effects of race/ethnicity on COVID-19 outcomes have not adjusted for differences in obesity rates.
In an editorial published in the International Journal of Obesity, Fatima Cody Stanford, MD, MPH, MPA, an obesity medicine physician-scientist at the Massachusetts General Hospital Weight Center, and colleagues discuss several factors that may explain disparities in COVID-19 outcomes.
Ethnic differences in economic status, underlying health conditions, neighborhood population density and household crowding all contribute to the unequal impact of COVID-19. In the U.K., which has more comprehensive data than the U.S. (as published by the Office for National Statistics), COVID-19 mortality was fourfold higher for Black individuals and threefold higher for Bangladeshi/Pakistani individuals than for white individuals.
However, adjustments for age, geography, educational attainment, level of deprivation and self-reported health only partially attenuated the higher risk.
Vitamin D Deficiency
Non-white ethnicity and obesity are each independently associated with vitamin D deficiency, which is one potential explanation for higher COVID-19 burden. The anti-inflammatory and antimicrobial properties of vitamin D help reduce the production of inflammatory cytokines and may help control the cytokine storm implicated in severe COVID-19.
A meta-analysis conducted before the COVID-19 pandemic concluded that vitamin D supplementation reduces the risk of acute respiratory tract infections, particularly in people who were very deficient (published in BMJ).
Inflammation Associated with Obesity
The chronic low-grade inflammatory state of obesity has been well described, but inflammatory changes may not be consistent across race/ethnicity. Two recent studies are instructive and found that:
- Black and Latinx children had a higher risk of low-grade inflammation than their white peers, and this effect was only partially mediated by parental education and body mass index (published in the Journal of Health and Social Behavior)
- During a weight-loss intervention among healthy women with BMI 27 to 30 kg/m2, fewer markers of inflammation decreased among Black women than white women (published in Obesity)
Health State and Behaviors
According to a new model, a person's health state, health behaviors and social behaviors interact with factors such as comorbidity burden to affect disease outcomes (published in The Lancet). Examples relevant to the racial/ethnic disparities in COVID-19 include:
- Higher rates and poorer control of comorbidities such as diabetes and cardiovascular disease, which is not fully considered in the studies that link obesity with COVID-19
- Greater occupational exposure to the novel coronavirus
- Structural barriers, notably language, that prevent access to public health messages about COVID-19, obesity and other chronic diseases
- Avoidance of medical care due to mistrust
A critical knowledge gap remains about how interactions between obesity, race/ethnicity and social class influence COVID-19 outcomes. In particular, the degree to which obesity and race/ethnicity are additive or multiplicative, mediators or confounders—and the degree to which obesity increases risk independent from its many comorbidities—have substantial implications for the medical and public health response to COVID-19.
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