Obesity and Mortality Among COVID-19 Patients

Quick Takes

  • Morbid obesity (BMI ≥40 kg/m2) is associated with an increased risk of death from COVID-19.
  • The association between BMI and death from COVID-19 is stronger in men and younger patients (≤60 years).

Study Questions:

How is body mass index (BMI) associated with death due to coronavirus disease 2019 (COVID-19)?


The authors conducted a retrospective cohort study of all Kaiser Permanente Southern California members diagnosed with COVID-19 from February 13 to May 2, 2020, identified through International Classification of Diseases, Tenth Revision (ICD-10) codes or laboratory testing. They examined the association between BMI and death within 21 days after diagnosis with COVID-19, stratified by whether or not they were hospitalized or intubated, and adjusting for individual-level factors such as race, sex, and clinical risk factors, in addition to neighborhood level factors such as population density and median income. The authors also explored the interaction between BMI, age, and sex.


Of a total of 6,916 patients with COVID-19 identified (45% male, 55% Hispanics, median age 49 years, and mean BMI of 30.6 kg/m2), 206 (3.0%) died. High BMI (≥40 kg/m2) was associated with a step-wise increase in the adjusted risk of death (2.7-fold increase for BMI 40-44, and 4-fold increase for BMI ≥45 kg/m2), compared to patients with normal BMI of 18.5-24. The impact of obesity on the risk of death was strongest in men and younger patients (≤60 years). Overall, the association was independent of whether patients were hospitalized or intubated, or of clinical risk factors.


Morbid obesity is associated with an increased risk of death, notably in men and patients ≤60 years of age.


This study expands our understanding of the association of obesity with death from COVID-19 in many ways. It confirms previous reports that younger obese patients are likely to do worse, and suggests that the relationship between obesity and death from COVID-19 is not related to comorbid risk factors, or racial or neighborhood level factors, which were thought to be confounders of that association. The findings highlight an unmet need: deciphering the mechanisms which link obesity to severe COVID-19. Obesity is a proinflammatory condition, associated with high levels of prothrombotic factors including angiotensin-II, also elevated in COVID-19. Understanding that link may yield valuable knowledge on the role obesity plays in numerous disease states beyond COVID-19.

Clinical Topics: COVID-19 Hub, Prevention

Keywords: Angiotensin II, Body Mass Index, Comorbidity, Coronavirus, COVID-19, Inflammation, Intubation, Obesity, Obesity, Morbid, Population Density, Primary Prevention, Risk Factors, severe acute respiratory syndrome coronavirus 2, Thrombosis

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