Obesity modifies the association of race and COVID-19 mortality: analysis of a retrospective cohort from Brazil

COVID-19 and obesity are two concurrent, interrelated pandemics that share similarities in their social causes, including racism. It is essential to understand how their characteristics are interrelated and the possible role of obesity in the association between race and COVID-19 mortality. We investigated the relationship between race and COVID-19 mortality and the modifying effect of obesity on this relationship. It is a retrospective cohort study. We analyzed data from 113,737 adults aged ≥ 19 years hospitalized for COVID-19 in Rio Grande do Sul, Brazil. The study outcome was in-hospital COVID-19 mortality. Exposures included race, analyzed as white, Brown, and Black individuals and as white vs. Brown and Black individuals, and obesity. The cumulative incidence of COVID-19 mortality was 33.46% (95% CI 33.18-33.74). Compared with white individuals, Brown individuals had a 39% higher likelihood of death from COVID-19 (95% CI 1.28-1.52), while Black individuals had a 30% higher likelihood (95% CI 1.20-1.41). Brown women with obesity had the greatest likelihood of COVID-19 mortality (1.64 [95% CI 1.27-2.13]) compared with all other groups. Obesity was an effect modifier of the association between race and COVID-19 mortality, increasing the likelihood of mortality in the group of Brown women.