The Impact of Body Mass Index on Intensive Care Unit Outcomes of Critically ill Patients

Aim: Conflicting results have been reported regarding the potential impact of obesity on intensive care unit (ICU) outcome. In some studies, lower mortality was reported in obese and morbid obese patients. This situation was defined as "obesity survival paradox". Due to these conflicting results, we aimed to evaluate the effects of body mass index (BMI) on ICU outcomes of critically ill patients.Methods: This is a retrospective cohort study of adult patients hospitalized in a tertiary ICU of university hospital between January 2015 and December 2019. Patients were categorized into four groups according to their BMIs. Demographic data, admission diagnoses, comorbidities, APACHE II scores, invasive and noninvasive mechanical ventilation (IMV and NIV) use, frequency of sepsis, SOFA scores, length of ICU and hospital stay and ICU outcome (mortality or discharge) were compared. SPSS Statistics for Windows v.23.0.was used for data analysis.Results: A total of 410 patients were included. According to BMIs, 42% were normal, 32% overweight, 20% obese and 6% morbid obese. The APACHE II score was significantly higher in the normal BMI group (p = 0.049). Sepsis was detected in 113 (28%) cases. Although the rate of sepsis was higher in normal BMI group (32%), no statistical difference was found between the groups (p=0.427). Ninety-three (23%) patients died of them 27% were normal, 24% were overweight, 15% were obese and 12% were morbid obese (p=0.05). While no difference was observed between the groups in terms of IMV use; the frequency and duration of NIV use was higher in obese and morbid obese patient groups (p<0.05).Conclusion: This study revealed that the APACHE II score and the mortality were significantly lower; and NIV use was significantly higher among patients with BMI >25. In order to better clarify the effects of BMI on ICU outcomes, prospective studies with larger patient populations should be performed.