Critical Care and Shock

The impact of body mass index on mechanical ventilation and outcomes of patients admitted to the hospital with COVID-19


Introduction: Multiple studies consistently demonstrate a link between higher body mass index (BMI) levels and unfavorable outcomes in individuals with coronavirus disease 2019 (COVID-19). This study aimed to assess the influence of BMI on COVID-19 outcomes and the need for mechanical ventilation.

Materials and methods: From March 2020 to February 2022, we conducted a retrospective cohort study involving adult patients admitted to a single center in Houston, Texas, with COVID-19 infection. Patients were categorized into five groups based on their treatment methods: Group 1 received invasive mechanical ventilation, Group 2 used bilevel positive airway pressure ventilation (BiPAP), Group 3 was on high flow nasal cannula (HFNC), Group 4 utilized both HFNC and BiPAP, and Group 5 included patients in the Intensive Care Unit (ICU) who could manage on room air.

Results: 985 individuals were included in this study with a median age of 55.7 years old (45-67). Overall median BMI was 29.3 kg/m2 (27-34.5 kg/m2). Five hundred fifty-four (56.2%) patients were males and 431 (43.8%) females. A total of 798 (81%) survived. Hospitalization survival in underweight patients was 13 (86.7%), normal weight was 143 (81.7%), overweight was 267 (79%), obese class 1 was 191 (84.1%), obese class 2 was 98 (79%), and obese class 3 was 87 (81.3%) (χ2 (5)=3.032, p=0.695). When assessing the need for mechanical ventilation, 160 (16.1%) of all patients required assisted ventilation. In each category: 3 (20%) underweight patients, 25 (16%) normal weight patients, 62 (39%) overweight patients, 33 (21%) obese class 1 patients, 23 (14%) obese class 2 patients, and 14 (9%) obese class 3 patients required ventilation (χ2 (5)=2.613, p=0.759). Analyzing days hospitalized, length of stay in each category was: underweight 6 (5-12) days, normal weight 7 (3-12) days, overweight 6.5 (4-12) days, obese class 1 7 (4-12) days, obese class 2 7.5 (4-14) days, and obese class 3 7 (5-12) days (H(5)=3.207, p=0.632).

Conclusions: In our cohort, BMI was not associated with increased mortality rate, longer hospitalization duration, or need for mechanical ventilation in patients with COVID-19.