Obesity, Ethnicity, and Covid-19 Mortality: A population-based cohort study of 12.6 Million Adults in England

ABSTRACT

ImportanceObesity and ethnicity are well characterised risk factors for severe COVID-19 outcomes, but the differential effects of obesity on COVID-19 outcomes by race/ethnicity has not been examined robustly in the general population. ObjectiveTo investigate the association between body mass index (BMI) and COVID-19 mortality across different ethnic groups. Design, Setting, and ParticipantsThis is a retrospective cohort study using linked national Census, electronic health records and mortality data for English adults aged 40 years or older who were alive at the start of pandemic (24th January 2020). ExposuresBMI obtained from electronic health records. Self-reported ethnicity (white, black, South Asian, other) was the effect-modifying variable. Main Outcomes and MeasuresCOVID-19 related death identified by ICD-10 codes U07.1 or U07.2 mentioned on the death certificate from 24th January 2020 until December 28th 2020. ResultsThe analysis included white (n = 11,074,708; mean age 61.9 [{+/-}13.4] years; 54% women), black (n = 416,542; 56.4 [{+/-}11.7] years; 57% women), South Asian (621,691; 55.7 [{+/-}12.4] years; 51% women) and other (n = 478,196; 55.3 [{+/-}11.6] years; 55% women) ethnicities with linked BMI data. The association between BMI and COVID-19 mortality was stronger in ethnic minority groups. Compared to a BMI of 22.5 kg/m2 in white ethnicities, the adjusted HR for COVID-19 mortality at a BMI of 30 kg/m2 in white, black, South Asian and other ethnicities was 0.95 (95% CI 0.87-1.03), 1.72 (1.52-1.94), 2.00 (1.78-2.25) and 1.39 (1.21-1.61), respectively. The estimated risk of COVID-19 mortality at a BMI of 40 kg/m2 in white ethnicities (HR = 1.73) was equivalent to the risk observed at a BMI of 30.1 kg/m2, 27.0 kg/m2, and 32.2 kg/m2 in black, South Asian and other ethnic groups, respectively. ConclusionsThis population-based study using linked Census and electronic health care records demonstrates that the risk of COVID-19 mortality associated with obesity is greater in ethnic minority groups compared to white populations. QuestionDoes the association between BMI and COVID-19 mortality vary by ethnicity? FindingsIn this study of 12.6 million adults, BMI was associated with COVID-19 in all ethnicities, but with stronger associations in ethnic minority populations such that the risk of COVID-19 mortality for a BMI of 40 kg/m2 in white ethnicities was observed at a BMI of 30.1 kg/m2, 27.0 kg/m2, and 32.2 kg/m2 in black, South Asian and other ethnicities, respectively. MeaningBMI is a stronger risk factor for COVID-19 mortality in ethnic minorities. Obesity management is therefore a priority in these populations.