Clinical paperA new age-based formula for estimating weight of Korean children

ObjectivesThe objective of this study was to develop and validate a new age-based formula for estimating body weights of Korean children.MethodsWe obtained body weight and age data from a survey conducted in 2005 by the Korean Pediatric Society that was performed to establish normative values for Korean children. Children aged 0-14 were enrolled, and they were divided into three groups according to age: infants (<12 months), preschool-aged (1-4 years) and school-aged children (5-14 years). Seventy-five percent of all subjects were randomly selected to make a derivation set. Regression analysis was performed in order to produce equations that predict the weight from the age for each group. The linear equations derived from this analysis were simplified to create a weight estimating formula for Korean children. This formula was then validated using the remaining 25% of the study subjects with mean percentage error and absolute error. To determine whether a new formula accurately predicts actual weights of Korean children, we also compared this new formula to other weight estimation methods (APLS, Shann formula, Leffler formula, Nelson formula and Broselow tape).ResultsA total of 124,095 children's data were enrolled, and 19,854 (16.0%), 40,612 (32.7%) and 63,629 (51.3%) were classified as infants, preschool-aged and school-aged groups, respectively. Three equations, (age in months + 9)/2, 2 × (age in years) + 9 and 4 × (age in years) − 1 were derived for infants, pre-school and school-aged groups, respectively. When these equations were applied to the validation set, the actual average weight of those children was 0.4 kg heavier than our estimated weight (95% CI = 0.37-0.43, p < 0.001). The mean percentage error of our model (+0.9%) was lower than APLS (−11.5%), Shann formula (−8.6%), Leffler formula (−1.7%), Nelson formula (−10.0%), Best Guess formula (+5.0%) and Broselow tape (−4.8%) for all age groups.ConclusionWe developed and validated a simple formula to estimate body weight from the age of Korean children and found that this new formula was more accurate than other weight estimating methods. However, care should be taken when applying this formula to older children because of a large standard deviation of estimated weight.