Association between admission body mass index and outcomes in critically ill children: A systematic review and meta-analysis

Background & aims: The association between nutritional status at pediatric intensive care unit (PICU) admission with clinical outcomes remains unclear. We conducted this systematic review to summarize the overall impact of PICU admission body mass index (BMI) on clinical outcomes. Methods: We searched the following medical databases from inception through May 2020: PubMed, Excerpta Medica database (Embase), Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, and Web of Science. We included studies on patients <18 years old admitted to a PICU that investigated the effect of BMI on mortality, PICU or hospital length of stay (LOS), or duration of mechanical ventilation (MV). Classification of underweight, overweight, and obese were based on each study's criteria. Results: There was a total of 21,558 patients from 20 included studies. 12,936 (60.0%), 2965 (13.8%), 2182 (10.1%), 3348 (15.5%) were normal weight, underweight, overweight, and obese patients, respectively. Relative to normal weight patients, underweight (OR 1.32, 95% CI 0.89-1.98; p = 0.171) and overweight/ obese patients (OR 1.10, 95% CI 0.86-1.42; p = 0.446) did not have an increase risk in mortality. There was also no difference in duration of MV, PICU and hospital LOS between all three weight categories. Included studies were heterogeneous and lacked standardized nutritional categorization. Sensitivity analysis including only studies that used BMI z-scores as nutritional classification (n = 5) revealed that underweight patients had higher odds of mortality compared to patients with normal weight (OR 1.61, 95% CI 1.35-1.92; p < 0.001); studies that used percentiles as classification did not reveal any differences in mortality. Sensitivity analysis including only studies containing mixed PICU cohorts (i.e., excluding specialized cohorts e.g., congenital heart surgeries, burns) revealed higher mortality odds in underweight patients (OR 1.53, 95% CI 1.25-1.87; p < 0.001) and overweight/obese patients (OR 1.51, 95% CI 1.14-2.01; p = 0.004) relative to normal weight patients. Conclusions: Our systematic review did not reveal any association between PICU admission BMI status and outcomes in critically ill children. Further investigation with standardized nutrition status classification on admission, stratified by patient subgroups, is needed to clarify the association between nutritional status and clinical outcomes of PICU patients. (c) 2021 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.