Can age-based estimates of weight be safely used when resuscitating children?

Prescribing medication appropriate to a child's bodily dimensions is fundamental to paediatric emergency medicine. Mathematical formulae are frequently used in clinical practice to estimate children's weights. In 1995 the UK's paediatric reference data, describing age-related changes in bodily proportions (both weight and height), were updated and published. This study assesses the validity of using mathematical estimates, age-based estimates or length-based estimates of weight (the latter both compiled from this reference data) by comparison with actual physical measurements recorded in a paediatric clinic setting.

A prospective study was carried out in a paediatric outpatient setting recording age, weight and height for statistical comparison with these three possible methods.

544 children aged 0-11 years were recruited, with mean (SD) age, weight and height of 5.3 (2.9) years, 21.4 (10) kg and 108 (22) cm, respectively.

Both length-based and age-based estimates of weight outperformed the currently accepted "gold standard" mathematical estimate when applied to children up to 11 years of age (approximately 35 kg). Length-based estimates were statistically superior, but the physical limitations and technical constraints posed when attempting to accurately measure a child's length in emergency environments may favour the simplicity of using the child's age against tables of growth chart reference data to provide an estimate of their weight.