Impact of Obesity on Risk of Severe COVID-19 Among Patients in England

Data from a cohort study of nearly 7 million patients in England is offering an overview of the impact BMI, type 2 diabetes, and other health conditions have had on COVID-19 severity during the pandemic.

Using information obtained from a database of more than 35 million patients, results of the study suggest a linear association exists between increasing BMI when exceeding 23 kg/m2 and risk of severe COVID-19, with this risk being most notable among patients younger than 40 years of age and Black patients.

“Our findings from this large population-based cohort emphasize that excess weight is associated with substantially increased risks of severe COVID-19 outcomes, and one of the most important modifiable risk factors identified to date,” wrote investigators.

With an interest in further exploration of associations between clinical characteristics and severity of COVID-19, a University of Oxford-led team designed the current study as a prospective, community-based cohort study of patient-level data from the QResearch database of general practices in England. Combining information from this database with linked data from Public Health England, investigators hoped to perform an analysis using Cox proportional hazard models to estimate risk of severe COVID-19 according to BMI.

With January 24, 2020-April 30, 2020 defined as the period of interest, investigators identified 6,910,695 patients 20-99 years of age with at least one BMI measurement for inclusion in their study. The overall study cohort had a mean BMI of 26.78 (SD, 5.9) kg/m², more than 50% of patients had a BMI greater than 25 kg/m², and approximately 70% were 59 years of age or younger. Outcomes of interest in the study were admission to a hospital, admission to an intensive care unit (ICU), and death from COVID-19.

Of the 6,910,695 patients included in the analyses, 13,503 were hospitalized with COVID-19, 1601 required ICU admission, and 5479 died from COVID-19. Investigators noted approximately 33% of patients with severe COVID-19 outcomes had type 2 diabetes and most people with severe COVID-19 were aged 60 years or older.

With a nadir define as a BMI of 23 kg/m², results of the analyses indicated the presence of a J-shaped association between BMI and admission to the hospital (adjusted hazard ratio [aHR] per kg/m² from the nadir: 1.05; 95% CI, 1.05-1.05) and death (aHR, 1.04; 95% CI, 1.04-1.05). Investigators also pointed out a linear association with ICU admission was observed across the whole BMI range (aHR, 1.10; 95% CI, 1.09-1.10).

Further analysis suggested there was a significant interaction between BMI and age and ethnicity. Specifically, a greater risk per kg/m² above the nadir was seen in patients 20-39 years of age (aHR, 1.09; 95% CI, 1.08-1.10) compared to those 80-100 years of age (aHR and among Black patients (aHR 1.07; 95% CI, 1.06-1.06) compared to White patients (aHR, 1.04; 95% CI, 1.04-1.05). Investigators noted the risk of hospital admission and ICU admission due to COIVD-19 associated with each unit increase of BMI was lower in patients with type 2 diabetes, hypertension, and cardiovascular disease than in those without these morbidities.

“Although as yet unproven, interventions that reduce weight might reduce the risk of severe COVID-19 outcomes in individuals. In the longer term, our findings highlight the need to work towards a healthy weight at a population level,” investigators wrote.

This study, “Associations between body-mass index and COVID-19 severity in 6.9 million people in England: a prospective, community-based, cohort study,” was published in The Lancet Diabetes and Endocrinology.