Study: Association Between Increasing BMI, Risk of Testing Positive for SARS-CoV-2

New research presented at the European Congress on Obesity reveals an association between increasing body mass index (BMI) and the risk of testing positive SARS-CoV-2.

Obesity-related factors, including changes to the innate and adaptive immune systems brought on by excess weight, are believed to be associated with an increased risk of contracting various viral diseases. This association between BMI and viral infection risk suggests that a similar relationship may also exist between an individual’s BMI and their risk of contracting SARS-CoV-2, according to the study authors.

The objective of the study, conducted by researchers at Chaim Sheba Medical Center, was to assess the relationship between BMI and likelihood testing positive in patients who were tested for SARS-CoV-2 at the largest medical center in the Middle East. The researchers analyzed the details of patients who had been tested for the virus during a 9-month period, collecting data on BMI, age, sex, and presence of comorbidities, including congestive heart failure, diabetes mellitus, hypertension, ischemic heart disease (IHD), stroke, and chronic kidney disease (CKD). The study did not look at COVID-19 mortality or outcomes, only the risk of testing positive, according to the press release.

At the start of the COVID-19 pandemic, the Chaim Sheba Medical Center introduced a policy in which all hospitalized patients were tested for COVID-19, regardless of their symptoms or reason for admission (whether they were suspected to have COVID-19, or for completely different reasons such as elective surgery, traffic accidents, etc). In total, 26,030 patients were tested across the study period between March 16, 2020, and December 31, 2020, and 1178 positive COVID-19 results were recorded.

The study authors found that the odds of testing positive for SARS-CoV-2 were significantly higher in patients who were overweight or obese compared to those with a normal BMI. The patients who were classified as overweight were 22% more likely to test positive than those of normal weight.

The likelihood of testing positive was even higher in patients with obesity relative to their normal weight counterparts, and those odds rose with increasing BMI. Class 1 obesity was linked to a 27% higher risk of testing positive, which increased to 38% for class 2 obesity, and an 86% higher risk in class 3 or morbid obesity.

The relationship between BMI and the probability of a patient testing positive remained significant even after adjusting for the age and sex of the patient and having accounted for any comorbidities that were present. The study authors found that every 1 kg/m2 rise in a patient’s BMI was associated with an increase of approximately 2% in the risk of testing positive for SARS-CoV-2.

Further, the study found both positive and negative associations between the risk of testing positive and the presence of comorbidities linked to obesity. Diabetes was associated with a 30% higher likelihood of testing positive, whereas the risk of testing positive was almost 6 times greater in patients with hypertension.

However, the study authors found that the odds of a positive test were 39%, 55%, and 45% lower among patients with a history of stroke, IHD, and CKD, respectively. There was no explanation for why patients with stroke, IHD, or CKD would have a lower risk of testing positive for SARS-CoV-2.

"As BMI rises above normal, the likelihood of a positive SARS-CoV-2 test result increases, even when adjusted for a number of patient variables,” the study authors said in the press release. “Furthermore, some of the comorbidities associated with obesity appear to either be associated with an increased risk of infection or to be protective."

REFERENCE

New study finds an association between increasing BMI and the risk of testing positive for SARS-CoV-2. EurekAlert! Published May 10, 2021. Accessed May 12, 2021. https://www.eurekalert.org/pub_releases/2021-05/eaft-nsf051021.php