The association between body mass index and mortality in septic older adults

There is limited evidence on the association between body mass index (BMI) and outcomes in older adults with sepsis. The purpose of this study was to explore the relationship between BMI and the clinical outcome in the older adults with sepsis. All older adults (age 65 or older) with sepsis were analyzed retrospectively in the Intensive Care Medical Information Mart (MIMIC)- IV database. The primary outcome was 30-day mortality. The relationship between BMI and 30-day mortality was estimated by multivariate logistic regression model. The interaction and stratified analysis were performed by sex, race, renal disease, congestive heart failure (CHF), diabetes, and chronic pulmonary disease. The total number of participants was 6604. After adjustment for potential covariates, there was a significant correlation between BMI and 30-day mortality. A 1 kg/m2 increase in BMI was associated with a 3 % decrease in 30-day mortality (adjusted HR = 0.97, 95 % CI: 0.96–0.98, P < 0.001). The correlation between BMI and 30-day mortality showed a statistically significant nonlinear association with an l-shaped curve (p = 0.001). Significant interactions were observed only for sex in the stratified analyses (P = 0.001). In this study, it was observed that a higher BMI is linked with better survival rates among older adults suffering from sepsis, while being underweight raises the risk of mortality. Notably, male patients with a higher BMI had a lower mortality risk compared to female patients.