Body Mass Index and Risk of COVID-19 Diagnosis, Hospitalization, and Death: A Cohort Study of 2 524 926 Catalans

J Clin Endocrinol Metab. 2021 Nov 19;106(12):e5030-e5042. doi: 10.1210/clinem/dgab546.


Context: A comprehensive understanding of the association between body mass index (BMI) and coronavirus disease 2019 (COVID-19) is still lacking.

Objective: To investigate associations between BMI and risk of COVID-19 diagnosis, hospitalization with COVID-19, and death after a COVID-19 diagnosis or hospitalization (subsequent death), accounting for potential effect modification by age and sex.

Design: Population-based cohort study.

Setting: Primary care records covering >80% of the Catalan population, linked to regionwide testing, hospital, and mortality records from March to May 2020.

Participants: Adults (≥18 years) with at least 1 measurement of weight and height.

Main outcome measures: Hazard ratios (HR) for each outcome.

Results: We included 2 524 926 participants. After 67 days of follow-up, 57 443 individuals were diagnosed with COVID-19, 10 862 were hospitalized with COVID-19, and 2467 had a subsequent death. BMI was positively associated with being diagnosed and hospitalized with COVID-19. Compared to a BMI of 22 kg/m2, the HR (95% CI) of a BMI of 31 kg/m2 was 1.22 (1.19-1.24) for diagnosis and 1.88 (1.75-2.03) and 2.01 (1.86-2.18) for hospitalization without and with a prior outpatient diagnosis, respectively. The association between BMI and subsequent death was J-shaped, with a modestly higher risk of death among individuals with BMIs ≤ 19 kg/m2 and a more pronounced increasing risk for BMIs ≥ 40 kg/m2. The increase in risk for COVID-19 outcomes was particularly pronounced among younger patients.

Conclusions: There is a monotonic association between BMI and COVID-19 diagnosis and hospitalization risks but a J-shaped relationship with mortality. More research is needed to unravel the mechanisms underlying these relationships.

Keywords: SARS-CoV-2; adiposity; electronic health records; fatality; hospitalization; obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Body Mass Index*
  • COVID-19 / diagnosis
  • COVID-19 / epidemiology
  • COVID-19 / etiology*
  • COVID-19 / mortality*
  • COVID-19 Testing
  • Cohort Studies
  • Female
  • Hospital Mortality
  • Hospitalization / statistics & numerical data*
  • Humans
  • Male
  • Middle Aged
  • Mortality
  • Risk Factors
  • Spain / epidemiology
  • Young Adult