A higher body mass index (BMI) is associated with increased risks for hospitalization and death due to severe infectious respiratory diseases, including COVID-19, a new study involving over 470,000 patients suggests.
The BMI is a tool used to estimate the amount of body fat based on the patient’s height and weight. In their study, scientists at the University of Oxford in the United Kingdom found that for every 10 units increase in BMI, there is an elevated risk for severe COVID-19 (hazard ratio 2.26), lower respiratory tract infections (LRTIs, hazard ratio 1.74), and severe upper respiratory tract infections (URTIs, hazard ratio 1.37).
“This study supports previous findings that 10-unit higher BMI is associated with about double the risk of severe COVID-19,” the scientists wrote. “In contrast, the limited previous evidence on the association of BMI with risk of severe LRTIs or URTIs shows substantial variation in the strength of these associations.”
The scientists calculated different BMI categories with the adjusted hazard ratios for all three types of infections. For those with a BMI ranging from 35 to 60, the respective hazard ratios are 2.38, 1.91, and 1.40 for COVID-19, LRTIs, and URTIs.
A BMI greater than 30 indicates that a person has obesity. Those with a BMI of 40 or higher are considered severely obese.
“The findings support individual and population-level approaches to reduce obesity and targeted vaccination programs for respiratory infections for individuals with a high BMI,” the Oxford scientists concluded.
For this study, the scientists looked at data from the UK Biobank, a biomedical database containing health information of more than 500,000 volunteers. They identified a total of 476,176 participants who received baseline assessments between 2006 and 2010. Almost all participants (94 percent) are white, and more than half (54 percent) are women, with a median age of 58 and a mean BMI of 27.4.
Over the course of a follow-up completed in 2021, 20,302 participants were hospitalized for or died of severe infectious respiratory disease.
Among those patients, 1,296 had COVID-19, 17,085 had LRTIs, and 1,504 had URTIs. Of the COVID-19 cases, 144 patients died without prior hospitalization.
