The relationship between obesity, calorie delivery and mortality in the critically ill: a post hoc analysis of The...

Evidence guiding calorie delivery in the critically ill with obesity is limited, and international guidelines are inconsistent.

This study aims to evaluate the relationship between enteral calorie delivery and mortality in critically ill patients with obesity.

Mechanically ventilated adult patients enrolled in The Augmented versus Routine Approach to Giving Energy Trial multicenter, double-blind, randomized trial evaluating 1.5 kcal/mL compared with 1 kcal/mL enteral nutrition at 1 mL/kg ideal body weight (IBW)/h were included in this post hoc analysis. Obesity was classified as BMI ≥30 kg/m². The primary outcome was the relationship between calorie delivery and 90-d mortality according to intensive care admission BMI with probability of death analyzed using a log binomial mixed model and reported as relative risk (RR) [95% confidence intervals (CIs)].

Thirty-six percent of patients (1436/3957) were obese at baseline, median (IQR) BMI: 34.9 (32.1, 40.0) kg/m². Mean (±SEM) daily calorie delivery for the group with obesity compared with the nonobese was 24.7 ± 0.2 and 24.2 ± 0.1 kcal/kg IBW, P = 0.018, respectively. By day 90, 313 of 1423 patients with obesity (22.2%) and 715/2491 patients without obesity (28.7%) had died; unadjusted RR: 0.766 (95% CI: 0.683, 0.860); P < 0.001. Results were unchanged after adjustment for trial site and baseline covariates. For both cohorts, probability of death by day 90 increased progressively below ∼20 kcal/kg IBW/d; however, between 20 and 36 kcal/kg IBW/d, probability of death was relatively stable. For the group with obesity, the threshold for probability of death varied according to the method of calculating body weight: ∼15 kcal/kg/d for obesity-adjusted body weight and ∼10 kcal/kg/d for actual body weight.

In this post hoc study of critically ill patients receiving enteral nutrition, obesity confers a relative survival advantage to 90 d. Reduced calorie delivery is associated with increased risk of death in the group with obesity and the nonobese, but calorie threshold for the group with obesity varies according to the method of body weight calculation. This study was registered at TARGET trial clinicaltrials.gov number as NCT02306746.