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

Emerg Med Australas. 2007 Dec;19(6):535-42. doi: 10.1111/j.1742-6723.2007.01031.x.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adolescent
  • Anthropometry / methods*
  • Body Weight*
  • Child
  • Child, Preschool
  • Humans
  • Infant
  • Pediatrics / methods*
  • Retrospective Studies
  • Triage