Impact of Body Mass Index on the Mortality of Critically Ill Patients Admitted to the Intensive Care Unit: An Observational Study

Background: Obesity is a severe multifactorial disorder that carries high morbidity and mortality. Objectives: This study aimed to evaluate the possible association between body mass index (BMI) and mortality in patients admitted to intensive care units (ICU). Methods: In this cross-sectional study, all patients admitted to the ICU were studied. The demographic characteristics, ICU, and hospital length of stay, organ failure, mortality, duration of mechanical ventilation, the occurrence of nosocomial infection, and type of admission were recorded for all patients. Patients were categorized based on their BMI. Results: In total, 502 patients were studied who 53.2% of them were male. Most of the death (28.6%) were recorded in the obesity class II patients, while the lowest rate (3.9%) was for the normal-weight patients (P value 0.001). The APACHE II and waist circumference had a statistically significant association with the mortality rate (P value 0.001). After adjusting for age and gender, a significant association was found between waist circumference and mortality rate (OR = 1.15, 95% CI = 1.03 - 1.29; P value = 0.014), APACHE II score, and mortality rate (OR = 2.79, 95% CI = 1.91 - 4.07, P value 0.001); but there was no significant association between BMI and mortality rate. Conclusions: This study demonstrated that BMI is associated with an increased risk of mortality, regardless of age and gender. However, after adjusting for age and gender as confounding factors, BMI didn’t have a significant effect on mortality, while the APACHE II score and waist circumference affected the mortality rate.