Obesity Linked to Reduced Risk for In-Hospital Mortality in Patients on ECMO Support

Patients receiving extracorporeal membrane oxygenation did not differ in regard to BSI risk when grouped by BMI category, but those with higher BMIs had reduced risk for in-hospital mortality.

Bloodstream infection (BSI) incidence does not significantly differ across BMI categories, but higher BMI is associated with reduced in-hospital mortality in patients receiving extracorporeal membrane oxygenation (ECMO), according to results of a study published in the Journal of Hospital Infection.

Patients who require ECMO are at increased risk for BSIs due to prolonged hospitalization. Although obesity is associated with poor clinical outcomes in critically ill patients, obesity may have a protective effect for certain clinical conditions.

Researchers conducted a retrospective, single-center study between January 2015 and May 2021. The researchers aimed to investigate the effects of BMI on BSI incidence and in-hospital mortality among adult patients receiving ECMO for more than 48 hours. The primary endpoint was the occurrence of BMI, and the secondary endpoint was in-hospital mortality. Both endpoints were assessed after patients were stratified by BMI category and infection type (bacteremia and candidemia). Cox proportional hazards regression was used to determine the risk for BSI across BMI categories, with adjustments for various clinical factors.

A total of 473 patients were included in the analysis and divided into 5 BMI-based groups (Groups 1-5: BMI, <18.5, 18.5-23.0, 23.0-25.0, 25.0-30.0, and >30.0 kg/m2, respectively). The mean age among the population ranged between 49.8 and 52.9 years, and the median duration of ECMO was 11.8 (IQR, 4.1-12.7) days.

The impact of obesity on the clinical outcomes of septic shock and ECMO management remains controversial.

The percentage of patients who developed BSIs did not significantly differ across BMI groups (range, 19%-28.7%; P =.591). There also was no significant between-group difference in regard to the occurrence of bacteremia or candidemia.

In contrast, the adjusted analysis showed that the risk for in-hospital mortality significantly differed across BMI groups (P =.025). Of note, the risk for in-hospital mortality was lower among patients in Group 4 compared with those in Group 2 (P =.004), indicating a protective effect for BMIs above the normal range.

Study limitations include the retrospective design, differences in patient demographics and comorbidities among the groups, and the lack of data on weight changes that may have occurred among the population.

According to the researchers, “The impact of obesity on the clinical outcomes of septic shock and ECMO management remains controversial.”


Lee EH, Lee JA, Ahn JY, et al. Association of body mass index and bloodstream infections in patients on extracorporeal membrane oxygenation: a single-centre retrospective cohort studyJ Hosp Infect. Published online August 8, 2023. doi:10.1016/j.jhin.2023.08.005