Best Guess method for age‐based weight estimation in paediatric emergencies: Validation and comparison with current methods

BACKGROUND: During paediatric resuscitation, drug doses are calculated based upon weight. Age-based weight estimates are used when weighing children is impractical. The average weight of Australian children has increased, and widely used paediatric age-based formulae might underestimate weight. A modified age-based method for paediatric weight calculation, the 'Best Guess', has been described. OBJECTIVE: To validate the Best Guess formulae on a new population of paediatric emergency patients, and to compare the accuracy of this method with Advanced Paediatric Life Support (APLS) and Australian Resuscitation Council (ARC) formulae for age-based weight calculations. METHODS: A retrospective study was performed of Australasian Triage Scale (ATS) category 1 or 2 patients presenting to a tertiary paediatric ED over a 12 month period. Calculated weights using each method (APLS, ARC and Best Guess) were compared with true weights for infants (<1 year), preschool-aged (1-4 years) and school-aged (5-14 years) children. Mean actual error and mean percentage error for each was calculated. RESULTS: A total of 1843 patient weights were included in the study. The Best Guess Infant formula accurately estimated weight (mean percentage error +4.2%). The Best Guess formulae more accurately estimated weight than both APLS and ARC formulae for both preschool-aged children (mean percentage error +2.6% vs-12.1% vs-12.1%) and school-aged children (mean percentage error +7.7% vs-19.9% vs-12.4%). CONCLUSION: The Best Guess formulae is a valid method for age-based weight estimation in acutely unwell or injured children presenting to the ED and more accurately predicts mean weight than either APLS or ARC formulae.