Obesity and COVID-19 severity

Clinical Question

Is obesity a risk factor for severe COVID-19?

Key Findings

  • Studies are showing that obesity is a significant risk factor for having severe COVID-19.
  • Obese patients have a high frequency of admittance to intensive care, need for invasive mechanical ventilation, and risk of developing severe pneumonia.

Summary of Information

Obesity and severity of disease

  • In an analysis of outcomes for 4103 patients confirmed to have COVID-19, the two greatest factors for admission to the hospital were age >65 and obesity. This studied showed via a multivariable analysis, that the factors most associated with hospitalization were age 75 years or older (OR 66.8, 95% CI, 44.7 to 102.6), age 65-74 (OR 10.9, 95% CI, 8.35 to 14.34), BMI>40 (OR 6.2, 95% CI, 4.2-9.3), and history of heart failure (OR 4.3 95% CI, 1.9-11.2).[1]
  • Patients aged < 60 years with a BMI of 30-34 were 2.0 times more likely to be admitted to acute care compared to those with a BMI < 30. These same patients were 1.8 times more likely to be admitted to critical care than patients with a BMI < 30. Patients with a BMI >35 and aged < 60 years were 2.2 times more likely to be admitted to acute care compared to patients in the same age category with a BMI < 30 (study size 3615 patients).[2]
  • In a preprint study of 387 COVID-19 patients, a multivariate analysis found the odds ratio for developing severe pneumonia was 1.86 (p=.05) for overweight patients and 3.42 (p< .01) for obese patients. However, when separated by gender, only obese men had a statistically significant correlation (n=32, OR 5.70, p< 0.01). While other gender/weight groups had OR >1, none reached statistical significance.[3]
  • In a study of 112 patients infected with COVID-19, patients were divided into a critical group and a general group. The BMI of the critical group (n=16) was significantly higher than that of the general group (n=96) (BMI 25.5 (CI 23.0, 27.5) vs. 22.0 (CI 20.0, 24.0), P=0.003). They then divided all 112 patients into a non-survivor group and survivor group. Among the non-survivors, 88.24% (n=15/17) of patients had a BMI> 25 kg/m(2), versus among the survivors, 18.95% (n=18/95) of patients had a BMI> 25 kg/m(2), (P< 0.001).[4]
  • In an investigation of 124 patients from a single hospital in France, the proportion of patients who required invasive mechanical ventilation was greatest in patients with BMI >35 kg/m2 and increased with BMI categories.[5]

Theories explaining why obesity leads to increase disease severity

  • There is a high level of expression of ACE2 in adipocytes (more ACE2 expressed in adipocytes than in lungs).[6] ACE2 is thought to be the receptor for the entry of COVID-19 into host cells.
  • Pulmonary function studies have shown a restrictive pattern and reduced lung volumes in obese individuals.[5]
  • Obesity can lead to type 2 inflammation in the lungs which may impact the lung parenchyma and bronchi.[5]
  • Abdominal obesity is characterized by abnormal secretion of adipokines and cytokines like TNF-a and interferon which may induce a defective immune response.[5]

Gaps in knowledge

It remains unclear why we are seeing a higher risk of severe disease in obese patients.

Author Information

Authors: Danielle Urman MS1; UC San Diego School of Medicine
Completed on: April 21, 2020
Last revised on: April 30, 2020

Reviewed by: Gary Smithson MD
Reviewed on: April 22, 2020

This summary was written as part of the CoRESPOND Earth 2.0 COVID-19 Rapid Response at UC San Diego. For more information about the project, please visit http://earth2-covid.ucsd.edu

References

  1. Petrilli CM, Jones SA, Yang J, et al. Factors associated with hospitalization and critical illness among 4,103 patients with COVID-19 disease in New York City. medRxiv. Published online April 11, 2020:2020.04.08.20057794. doi:10.1101/2020.04.08.20057794
  2. Lighter J, Phillips M, Hochman S, et al. Obesity in patients younger than 60 years is a risk factor for Covid-19 hospital admission. Clin Infect Dis. 2020.  [PMID:32271368]
  3. Qingxian C, Chen F, Fang L, et al. Obesity and COVID-19 Severity in a Designated Hospital in Shenzhen, China. Published online March 13, 2020. doi:10.2139/ssrn.3556658
  4. Peng YD, Meng K, Guan HQ, et al. [Clinical characteristics and outcomes of 112 cardiovascular disease patients infected by 2019-nCoV]. Zhonghua Xin Xue Guan Bing Za Zhi. 2020;48(0):E004.  [PMID:32120458]
  5. Simonnet A, Chetboun M, Poissy J, et al. High Prevalence of Obesity in Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Requiring Invasive Mechanical Ventilation. Obesity (Silver Spring). 2020.  [PMID:32271993]
  6. Jia X, Yin C, Lu S, et al. Two Things about COVID-19 Might Need Attention. Published online February 23, 2020. doi:10.20944/preprints202002.0315.v1