Persons with high body mass index (BMI) are at a higher risk of hospitalization or mortality on account of severe respiratory infections including lower and upper respiratory tract infections and not just Covid-19, according to a new study published in JAMA.^1,2 The risk for severe infection was highest in those in BMI category of 35-60.

A team of researchers from the University of Oxford, England examined the associations between BMI and risk of hospitalization or related mortality due to COVID-19 and respiratory tract infections, both upper and lower. For this, the data was sourced from the UK Biobank from 2006 to 2010. A total of 476,176 participants were included in the final analysis. Their median age was 58 and more than half (54%) were women. The mean BMI was 27.4. Patients with known respiratory diseases or who required hospitalization for a respiratory infection earlier were not included in the trial. Over a mean follow-up of 11.8 years, 20,302 study subjects required hospitalization or died because of severe infectious respiratory disease. Of these, 1296 were for Covid-19, 17,085 were for LRTIs and 1504 were for URTIs.

Analysis of data revealed that the incidence rate for Covid-19 was 1.2 per 1000 person-years in subjects with BMI less than 25. The incidence rate increased to 5.8 among those with BMI ranging from 35 to 60. For LRTIs, the incidence rates were 25.6 per 1000 person-years to 55.5 per 1000 person-years. For URTIs, the incidence rates were 2.2 per 1000 person-years to 4.4 per 1000 person-years.

The hazard ratios for Covid-19, LRTIs and URTIs for different BMI categories were calculated. Variables like age, sex, region, race, deprivation score, education, smoking and alcohol intake were adjusted for when analysing the data. For Covid-19, the HR was 0.62 for BMI <25 and 2.38 for BMI category 35-60. For LRTIs, the HR was 1.02 for BMI category <25 and 1.91 for BMI ranging from 35 to 60. And for URTIs, the HR was 0.79 among participants with BMI <25 and 1.40 for those with BMI 35 to 60.

These findings illustrate the high risk of severe infectious respiratory diseases among participants with high BMI. The risk for severe Covid-19 was found to increase by more than 2-folds among the high BMI category. These findings signify the need to maintain a healthy body weight to reduce the risk of severe infectious respiratory disease.

References

1. Bohrmann B, et al. Body mass index and risk of hospitalization or death due to lower or upper respiratory tract infection. JAMA. 2023 May 2;329(17):1512-1514. doi: 10.1001/jama.2023.2619.
2. https://www.hcplive.com/view/higher-bmi-increases-risk-of-severe-covid-19-respiratory-infections, May 3, 2023. Accessed on May 6, 2023.