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Overweight or obese patients risk more severe COVID-19 — 11-country analysis

Patients who are overweight or obese have more severe COVID-19 and are highly likely to require invasive respiratory support, according to a new international study. The research, led by the Murdoch Children's Research Institute (MCRI) and The University of Queensland found obese or overweight patients are at high risk for having worse COVID-19 outcomes. They are also more likely to require oxygen and invasive mechanical ventilation compared to those with a healthy weight.

MCRI researcher Dr Danielle Longmore said the findings, which highlighted the relationship between obesity and increased COVID-19 disease burden, showed the need to urgently introduce strategies to address the complex socio-economic drivers of obesity, and public policy measures such as restrictions on junk food advertising.

"Although taking steps to address obesity in the short-term is unlikely to have an immediate impact in the COVID-19 pandemic, it will likely reduce the disease burden in future viral pandemics and reduce risks of complications like heart disease and stroke," she said.

The study looked at hospitalised SARS-CoV-2 patients from 18 hospitals in 11 countries including China, America, Italy, South Africa and The Netherlands.

Among the 7,244 patients aged 18 years and over, 34.8% were overweight and 30.8% were obese.

COVID-19 patients with obesity were more likely to require oxygen and had a 73% greater chance of needing invasive mechanical ventilation. Similar but more modest results were seen in overweight patients. No link was found between being overweight or obese and dying in hospital from COVID-19.

Cardiovascular and pre-existing respiratory diseases were associated with increased odds of in-hospital deaths but not a greater risk for needing oxygen and mechanical ventilation. For patients with pre-existing diabetes, there was increased odds of needing invasive respiratory support, but no additionally increase in risk in those with obesity and diabetes.

Men were at an increased risk of severe COVID-19 outcomes and needing invasive mechanical ventilation. In those aged over 65 years, there was an increased chance of requiring oxygen and higher rates of in-hospital deaths.

The University of Queensland's Dr Kirsty Short, who co-led the research, said almost 40% of the global population was overweight or obese.

"Obesity is associated with numerous poor health outcomes, including increased risk of cardiometabolic and respiratory disease and more severe viral disease including influenza, dengue and SARS-CoV-1," she said.

Short said while previous reports indicated that obesity was an important risk factor in the severity of COVID-19, almost all this data had been collected from single sites and many regions were not represented. Moreover, there was a limited amount of evidence available about the effects of being overweight or obese on COVID-19 severity.

"Given the large scale of this study we have conclusively shown that being overweight or obese are independent risk factors for worse outcomes in adults hospitalised with COVID-19," she said.

MCRI Professor David Burgner, who co-led the research, said the data would help inform immunisation prioritisation for higher-risk groups.

"At the moment, the World Health Organisation has not had enough high-quality data to include being overweight or obese as a risk factor for severe COVID-19 disease. Our study should help inform decisions about which higher-risk groups should be vaccinated as a priority," he said.

Researchers from Radboud University Medical Centre in The Netherlands, University of Bern in Switzerland, the Doherty Institute, University of Queensland, Washington University, Melbourne University, Monash University and an international BMI-COVID consortium also contributed to the study.


Study details
Diabetes and Overweight/Obesity Are Independent, Nonadditive Risk Factors for In-Hospital Severity of COVID-19: An International, Multicenter Retrospective Meta-analysis

Danielle K Longmore, Jessica E. Miller, Siroon Bekkering, Christoph Saner, Edin Mifsud, Yanshan Zhu, Richard Saffery, Alistair Nichol, Graham Colditz, Kirsty R Short, David P Burgner

Published in Diabetes Care in April 2021

Obesity is an established risk factor for severe coronavirus disease 2019 (COVID-19), but the contribution of overweight and/or diabetes remains unclear. In a multicenter, international study, we investigated if overweight, obesity, and diabetes were independently associated with COVID-19 severity and whether the BMI-associated risk was increased among those with diabetes.
Research design and Methods
We retrospectively extracted data from health care records and regional databases of hospitalized adult patients with COVID-19 from 18 sites in 11 countries. We used standardized definitions and analyses to generate site-specific estimates, modeling the odds of each outcome (supplemental oxygen/noninvasive ventilatory support, invasive mechanical ventilatory support, and in-hospital mortality) by BMI category (reference, overweight, obese), adjusting for age, sex, and prespecified comorbidities. Subgroup analysis was performed on patients with preexisting diabetes. Site-specific estimates were combined in a meta-analysis.
Among 7,244 patients (65.6% overweight/obese), those with overweight were more likely to require oxygen/noninvasive ventilatory support (random effects adjusted odds ratio [aOR], 1.44; 95% CI 1.15–1.80) and invasive mechanical ventilatory support (aOR, 1.22; 95% CI 1.03–1.46). There was no association between overweight and in-hospital mortality (aOR, 0.88; 95% CI 0.74–1.04). Similar effects were observed in patients with obesity or diabetes. In the subgroup analysis, the aOR for any outcome was not additionally increased in those with diabetes and overweight or obesity.
In adults hospitalized with COVID-19, overweight, obesity, and diabetes were associated with increased odds of requiring respiratory support but were not associated with death. In patients with diabetes, the odds of severe COVID-19 were not increased above the BMI-associated risk.


Murdoch Children’s Research Institute material

Diabetes Care study (Restricted access)


See also MedicalBrief archives:

Super-spreaders: Exhale increases with COVID-19 infection, age, and obesity

Relationship between COVID-19 deaths and morbid obesity — large US analysis

Increasingly a link found between obesity and COVID-19 outcome risk

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