title: Comparison of 3 body size descriptors in critically ill obese children and adolescents: implications for medication dosing.
abstract: OBJECTIVE
  To compare 3 methods of weight determination for medication dose calculations in obese children and to discuss feasibility for use in routine care.
  
  
  METHODS
  This was a patient safety and quality improvement study evaluating patients (2-19 years old) admitted to the pediatric intensive care unit during a 13-month period (July 2010-July 2011). Patients identified as obese (≥95th percentile body mass index [BMI] for age), including severely obese (≥99th percentile BMI for age), were included in the weight method comparison portion of this study. Lean body mass estimations, using equations derived by the Peters and Foster methods, were compared to ideal body weight estimates by using the BMI method. Absolute differences between values generated by the 3 methods, intraclass correlation (ICC), and Bland-Altman plots were calculated.
  
  
  RESULTS
  A total of 1369 patients met initial criteria; 176 met criteria for the dosing weight comparison (age ± SD = 9.28 ± 5 years; actual weight ± SD = 55.5 ± 33.9 kg; 46% female). Sixty were severely obese and 116 were obese. Mean ICC between methods was 0.968 (95% Confidence interval (CI): 0.959, 0.975). The Peters method estimated higher weights than the Foster or BMI method. Bland-Altman plots illustrated good agreement between methods in children with weight below 50 kg, but decreased agreement above 50 kg, which was influenced by sex.
  
  
  CONCLUSIONS
  All methods demonstrated strong correlation and acceptable agreement in children below 50 kg. Systematic biases were identified in children above 50 kg where variance was higher. The BMI method was least complex to calculate and the most feasible method for daily use.
authors.affiliation: Department of Clinical Pharmacy, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Ross
authors.affiliation: Department of Clinical Pharmacy, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Jorgensen
authors.affiliation: Colorado School of Public Health, Biostatistics and Informatics, Colorado Biostatistics Consortium, Research Consulting Lab, University of Colorado Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Peter E
authors.initials: PE
authors.lastname: DeWitt
authors.affiliation: Pediatric Intensive Care Unit, Section of Critical Care Medicine.
authors.forename: Carol
authors.initials: C
authors.lastname: Okada
authors.affiliation: Department of Pediatrics, Section of Nutrition Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Renee
authors.initials: R
authors.lastname: Porter
authors.affiliation: Department of Pediatrics, Section of Nutrition Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Matthew
authors.initials: M
authors.lastname: Haemer
authors.affiliation: Department of Clinical Pharmacy, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Reiter
keywords: body mass index; ideal body weight; lean body mass; obesity; pediatric