Prediction of height and body mass index based on body segments: Use of Gauld's equations in an Argentine sample

When height cannot be measured or does not account for actual bone growth in children, due to their condition, it may be estimated using equations based on body segments.

1. To compare observed height (OH) and predicted height (PH) based on body segments using the equations of Gauld et al. 2. To analyze its applicability in the estimation and interpretation of body mass index (BMI).

A sample of children and adolescents without musculoskeletal alterations. Height, arm span, length of the ulna, the forearm, the tibia and the leg, weight, and pubertal development were registered. BMI was estimated. Differences and agreements between OH and PH were analyzed using the Bland-Altman method and an intraclass correlation coefficient. For BMI, the absolute prediction error and agreement were estimated using a Kappa coefficient.

Two hundred and twenty children and adolescents aged 6.04-19.1 years were included. The intraclass correlation coefficient between PH and OH was > 0.9 in all equations. In average, PH overestimated OH by less than 2.0 cm, except when using the ulna length (2.6 cm among girls and 3.4 m among boys). The average absolute prediction error for BMI was < 5 %, except for the ulna length, and the Kappa coefficient was > 0.7.

In our sample, the equations of Gauld et al. were adequate to predict height and estimate BMI. The greatest difference between observed height and predicted height was observed when using the ulna length.