Paediatric weight estimation by age in the digital era: optimising a necessary evil

Age-based weight estimation methods are regularly used in paediatric emergency medicine despite their well-established inaccuracy.

Determine the potential improvement in accuracy achievable by the use of a new mobile application, based on CDC/WHO weight-for-age centile data, which incorporates a gender assignment, a body habitus assessment, and which is capable of an age-in-months based calculation.

A theoretical, simulated validation study, comparing the performance of the widely used APLS/EPALS formulae against two contemporary habitus-adjusted methods, and the Helix Weight Estimation Tool. 1,070,743 children from the 2015/2016 UK National Child Measurement Program dataset, aged between 4 and 5 and 11 and 12 years, had age-based weight estimates made by all five methods.

Primary outcomes were the percentage of weight estimations within 10%, 20%, and those greater than 20% discrepant from actual weight for each method. Our theoretical, gender-dependent, habitus-adjusted method performed better than all other methods across all error thresholds. The overall number of estimations within 10% was 70.4%, and within 20% was 95.45%. The mean percentage error was -1% compared to actual weight.

The use of a digital tool incorporating a subjective assessment of body habitus, gender assignment, and the ability to estimate weight based on age-in-months might be able optimise the process of paediatric weight estimation by age, making this practice as safe and accurate as possible for the occasions when weight estimation by age is chosen over length-based methods.