Weight as a Risk Factor for Mortality in Critically Ill Patients

Abstract

Objectives: To explore the hypothesis that obesity is associated with increased mortality and worse outcomes in children who are critically ill.

Methods: Secondary analysis of the Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology study, a prospective, multinational observational study. Patients between 3 months and 25 years across Asia, Australia, Europe, and North America were recruited for 3 consecutive months. Patients were divided into 4 groups (underweight, normal weight, overweight, and obese) on the basis of their BMI percentile for age and sex.

Results: A total of 3719 patients were evaluated, of whom 542 (14%) had a primary diagnosis of sepsis. One thousand fifty-nine patients (29%) were underweight, 1649 (44%) were normal weight, 423 (11%) were overweight, and 588 (16%) were obese. The 28-day mortality rate was 3.6% for the overall cohort and 9.1% for the sepsis subcohort and differed significantly by weight status (5.8%, 3.1%, 2.2%, and 1.8% for subjects with underweight, normal weight, overweight, and obesity, respectively, in the overall cohort [P < .001] and 15.4%, 6.6%, 3.6%, and 4.7% in the sepsis subcohort, respectively [P = .003]). In a fully adjusted model, 28-day mortality risk was 1.8-fold higher in the underweight group versus the normal weight group in the overall cohort and 2.9-fold higher in the sepsis subcohort. Patients who were overweight and obese did not demonstrate increased risk in their respective cohorts. Patients who were underweight had a longer ICU length of stay, increased need for mechanical ventilation support, and a higher frequency of fluid overload.

Conclusions: Patients who are underweight make up a significant proportion of all patients in the PICU, have a higher short-term mortality rate, and have a more complicated ICU course.

Trial registration: ClinicalTrials.gov NCT01987921.

FIGURE 1

Screening, eligibility, and weight categories with 28-day mortality (primary outcome).

FIGURE 2

A and B, Kaplan-Meier survival curves and number at risk for the overall cohort and sepsis cohort. The number at risk for death in each weight group is presented below the figure in 5-day intervals, corresponding to the axis labels. For underweight versus all other groups, P < .005 for all comparisons in the overall cohort and P < .02 for all comparisons in the sepsis cohort.