A new analysis of existing research confirms a stark link between excess weight and COVID-19:
Obese patients faced the greatest bump in risk on the hospitalization front, with their odds of being admitted listed as 113% higher. The odds of diagnosis, ICU admission, and death were 46% higher (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.30-1.65; P < .0001); 74% higher (OR, 1.74, CI, 1.46-2.08, P < .0001); 48% (OR, 1.48, CI, 1.22–1.80, P < .001, all pooled analyses and 95% CI), respectively. All differences were highly significantly different, investigators reported in a systematic review and meta-analysis published online Aug. 26 in Obesity Reviews.
“Essentially, these are pretty scary statistics,” nutrition researcher and study lead author Barry M. Popkin, PhD, of the University of North Carolina at Chapel Hill School of Public Health, said in an interview. “Other studies have talked about an increase in mortality, and we were thinking there’d be a little increase like 10% – nothing like 48%.”
According to the Johns Hopkins University of Medicine tracker, nearly 6 million people in the United States had been diagnosed with COVID-19 as of Aug. 30. The number of deaths had surpassed 183,000.
The authors of the new review launched their project to better understand the link between obesity and COVID-19 “all the way from being diagnosed to death,” Dr. Popkin said, adding that the meta-analysis is the largest of its kind to examine the link.
Dr. Popkin and colleagues analyzed 75 studies during January to June 2020 that tracked 399,461 patients (55% of whom were male) diagnosed with COVID-19. They found that 18 of 20 studies linked obesity with a 46% higher risk of diagnosis, but Dr. Popkin cautioned that this may be misleading. “I suspect it’s because they’re sicker and getting tested more for COVID,” he said. “I don’t think obesity enhances your likelihood of getting COVID. We don’t have a biological rationale for that.”
The researchers examined 19 studies that explored a link between obesity and hospitalization; all 19 found a higher risk of hospitalization in patients with obesity (pooled OR, 2.13). Twenty-one of 22 studies that looked at ICU admissions discovered a higher risk for patients with obesity (pooled OR, 1.74). And 27 of 35 studies that examined COVID-19 mortality found a higher death rate in patients with obesity (pooled OR, 1.48).
The review also looked at 14 studies that examined links between obesity and administration of invasive mechanical ventilation. All the studies found a higher risk for patients with obesity (pooled OR, 1.66; 95% CI, 1.38-1.99; P < .0001).
Could socioeconomic factors explain the difference in risk for people with obesity? It’s not clear. According to Dr. Popkin, most of the studies don’t examine factors such as income. While he believes physical factors are the key to the higher risk, he said “there’s clearly a social side to this.”
On the biological front, it appears that “the immune system is much weaker if you’re obese,” he said, and excess weight may worsen the course of a respiratory disease such as COVID-19 because of lung disorders such as sleep apnea.
In addition to highlighting inflammation and a weakened immune system, the review offers multiple explanations for why patients with obesity face worse outcomes in COVID-19. It may be more difficult for medical professionals to care for them in the hospital because of their weight, the authors wrote, and “obesity may also impair therapeutic treatments during COVID-19 infections.” The authors noted that ACE inhibitors may worsen COVID-19 in patients with type 2 diabetes.
The researchers noted that “potentially the vaccines developed to address COVID-19 will be less effective for individuals with obesity due to a weakened immune response.” They pointed to research that suggests T-cell responses are weaker and antibody titers wane at a faster rate in people with obesity who are vaccinated against influenza.
Pulmonologist Joshua L. Denson, MD, MS, of Tulane University, New Orleans, praised the review in an interview, but noted that some of the included studies have wide confidence intervals. One study that links COVID-19 to a sixfold higher mortality rate (OR, 6.29) has a confidence interval of 1.76-22.45.
Dr. Denson said he’s seen about 100 patients with COVID-19, and many are obese and have metabolic syndrome.
Like the authors of the study, he believes higher levels of inflammation play a crucial role in making these patients more vulnerable. “For whatever reason, the virus tends to really like that state. That’s driving these people to get sick,” he said.
Moving forward, Dr. Popkin urged physicians to redouble their efforts to warn patients about the risks of obesity and the importance of healthy eating. He also said COVID-19 vaccine researchers must stratify obese vs. nonobese subjects in clinical trials.
The review was funded by Bloomberg Philanthropies, the Carolina Population Center, World Bank, and Saudi Health Council. The review authors report no relevant disclosures. Dr. Denson reports no relevant disclosures.
SOURCE: Popkin BM et al. Obes Rev. 2020 Aug 26. doi: 10.1111/obr.13128.