Obesity Paradox in Patients Hospitalized with Community Acquired Sepsis: Does Age Make a Difference?

Background: Higher body mass index (BMI) has been shown to be a protective factor from mortality in sepsis patients. Yet, whether this effect is different in the very elderly is currently unknown.
Objectives: To investigate the relationship between BMI and sepsis outcomes in patients older and younger than 80 years of age.
Methods: A retrospective analysis of consecutive patients admitted with sepsis to Shamir Medical Center, Israel, was conducted. We compared patients older than and younger than 80 years of age with a BMI higher and lower than 25 kg/m² for hospitalization outcomes.
Results: Patients older than 80 years presented with multiple co-morbidities compared to younger patients, but with no difference between BMI groups. Similarly, hospitalization outcomes of functional deterioration, discharge to long-term care facilities, and readmission were not significantly different between BMI groups in the same age category. Mortality was significantly different between BMI groups in patients older than 80 years of age, with higher mortality in BMI < 25 kg/m²: in-hospital mortality (23.4% vs. 14.9%, P < 0.001), 30-day mortality (27.6% vs. 17.9%, P < 0.001), and 90-day mortality (43.4% vs. 28.9%, P < 0.001). This difference was not significant between the groups younger than 80 years old. On logistic regression, BMI over 25 kg/m² was protective in all mortality categories. Nevertheless, there was no significant interaction between age over 80 years to BMI over 25 kg/m² in all mortality outcomes.
Conclusions: Among patients hospitalized with sepsis, higher BMI is a protective factor against mortality in both elderly and younger patients.