Evidence Matters

Cochrane Review: Is Obesity an Independent Risk Factor for COVID-19 Severity?

BACKGROUND AND PURPOSE:

Tadayon Najafabadi et al. (Cochrane Database of Systematic Reviews, 2023) assess whether obesity as an independent prognostic factor for COVID-19 severity and mortality

Systematic review and meta-analysis
Study inclusion criteria
- Case-control, case-series, prospective and retrospective cohort studies, secondary analyses of RCTs
- Studies that evaluated associations between obesity and COVID-19 adverse outcomes
- Studies needed to adjust for at least one factor other than obesity to be eligible
Study design
- Obesity classes
  - No obesity: BMI 18.5 to 24.9 kg/m2
  - Class I: BMI 30 to 35 kg/m2
  - Class II: BMI 35 to 40 kg/m2
  - Class III: BMI 40 kg/m2 and above
- Random-effects meta-analyses were used to generate pooled estimated of association
  - Meta-analyses for each obesity class were conducted separately for the main comparison
  - Meta-analysis of unclassified obesity and obesity as a continuous variable (5 kg/m2 increase in BMI) was also performed
- Risk of bias was assessed
- Certainty of evidence was determined using GRADE criteria
Primary outcome
- COVID-19-related mortality and other severe adverse outcomes

149 studies included in meta-analysis
Compared to patients without obesity, patients with obesity class I or II were not at increased odds of mortality
- Class I
  - OR 1.04 (95% CI, 0.94 to 1.16)High certainty evidence | 15 studies | 335,209 participants
- Class II
  - OR 1.16, 95% CI, 0.99 to 1.36
  - High certainty | 11 studies | 317,925 participants
Class III obesity may be at increased risk of COVID-19-related mortality
- Class III
  - OR 1.67 (95% CI, 1.39 to 2.00)
  - Low certainty | 19 studies | 354,967 participants
There was increased odds of mechanical ventilation with higher classes of obesity
- Class I
  - OR 1.38 (95% CI, 1.20 to 1.59)
- - Moderate certainty | 10 studies | 187,895 participants
  Class II
  - OR 1.67 (95% CI, 1.42 to 1.96)
- - High certainty | 6 studies | 171,149 participants
- Class III
  - OR 2.17 (95% CI, 1.59 to 2.97)
  - High certainty | 12 studies | 174,520 participants
There was no dose-response relationship across increasing obesity classifications for ICU admission and hospitalization

Class III obesity may increase the risk of mortality related to COVID-19
All classes of obesity appear to be associated with increased odds of mechanical ventilation in a dose-dependent manner