Obesity Increases the Severity and Mortality of Influenza and COVID-19: A Systematic Review and Meta-Analysis

Abstract

Since December 2019, COVID-19 has aroused global attention. Studies show the link between obesity and severe outcome of influenza and COVID-19. Thus, we aimed to compare the impacts of obesity on the severity and mortality of influenza and COVID-19 by performing a meta-analysis. A systematic search was performed in MEDLINE, EMASE, ClinicalTrials.gov, and Web of Science from January 2009 to July 2020. The protocol was registered onto PROSPERO (CRD42020201461). After selection, 46 studies were included in this meta-analysis. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were analyzed. We found obesity was a risk factor for the severity and mortality of influenza (ORsevere outcome = 1.56, CI: 1.28-1.90; ORmortality = 1.99, CI: 1.15-3.46). For COVID-19, obesity was a significant risk factor only for severe outcome (OR = 2.07, CI: 1.53-2.81) but not for mortality (OR = 1.57, CI: 0.85-2.90). Compared with obesity, morbid obesity was linked with a higher risk for the severity and mortality of both influenza (OR = 1.40, CI: 1.10-1.79) and COVID-19 (OR = 3.76, CI: 2.67-5.28). Thus, obesity should be recommended as a risk factor for the prognosis assessment of COVID-19. Special monitoring and earlier treatment should be implemented in patients with obesity and COVID-19.

Poor Metabolic Health Increases COVID-19-Related Mortality in the UK Biobank Sample

“…The results of our study are in line with previous reports linking obesity and individual components of metabolic health with poor COVID-19 outcomes and death (1,5,7,10,12,18,37). In particular, the fact that waist circumference was related to COVID-19 mortality is consistent with a study showing that visceral adipose tissue is significantly related to the risk of admission to an intensive care unit in COVID-19 patients (38).…”

“…Since the beginning of the COVID-19 pandemic, mounting evidence supports an association between obesity and poor outcomes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). The association holds for both obesity and obesityassociated metabolic healthhypertension, diabetes, dyslipidemia, and systemic inflammation (13).…”

A Comprehensive Review of Almond Clinical Trials on Weight Measures, Metabolic Health Biomarkers and Outcomes, and the Gut Microbiota

“…Poor quality diets are associated with progressively increasing weight gain, which can often lead to increased risk of central obesity and metabolic syndrome that can trigger a cascade of chronic disease risk factors, such as dyslipidemia, elevated blood glucose, hypertension, insulin resistance, increased systemic inflammation, and colonic microbiota dysfunction [106]. Obesity can also exacerbate severe adverse outcomes of influenza or COVID-19, associated with: (1) excessive abdominal fat, which pushes up on the diaphragm, causing the large muscle laying below the chest to restrict lung expansion and airflow, interfering with the delivery of oxygenated blood to the lower lung lobes, (2) increased risk for blood clotting, (3) weakened immune function because fat cells infiltrate immune organs such as the spleen, bone marrow, and thymus, making them less effective, and (4) elevated chronic, systemic low-grade inflammation, as fat cells are a major source of inflammation cytokines [107][108][109].…”

Cardiopulmonary Pathophysiological Aspects in the Context of COVID-19 and Obesity

“…In the context of the COVID-19 outbreak, clinical severity may be partially attributable to the underlying myocardial abnormalities, metabolic disorders, and pre-existing cardiovascular disorders in obese patients. A subset of meta-analyses have recently been published, underscoring the association between obesity and critical illness in terms of the need for ICU admission or invasive mechanical ventilation and mortality from COVID-19 [ 46 – 49 ]. In the meta-analysis by Yang et al [ 47 ], obesity was associated with COVID-19 severity (OR 2.31; 95% CI, 1.3–4.12).…”

“…The association between obesity and severity is particularly relevant in younger obese COVID-19 patients (OR 3.3) [ 48 ]. Zhao et al [ 49 ] reported an OR of 2.07 (95% CI 1.53–2.81) between obesity and severe outcomes of COVID-19. Finally, obesity was found to be a risk factor for COVID-19 severity independent of cardiovascular disorders and diabetes [ 50 ].…”