Validation of adult height prediction based on automated bone age determination in the Paris Longitudinal Study of healthy children

Background An adult height prediction model based on automated determination of bone age was developed and validated in two studies from Zurich, Switzerland. Varied living conditions and genetic backgrounds might make the model less accurate. Objective To validate the adult height prediction model on children from another geographical location. Materials and methods We included 51 boys and 58 girls from the Paris Longitudinal Study of children born 1953 to 1958. Radiographs were obtained once or twice a year in these children from birth to age 18. Bone age was determined using the BoneXpert method. Radiographs in children with bone age greater than 6 years were considered, in total 1,124 images. Results The root mean square deviation between the predicted and the observed adult height was 2.8 cm for boys in the bone age range 6–15 years and 3.1 cm for girls in the bone age range 6–13 years. The bias (the average signed difference) was zero, except for girls below bone age 12, where the predictions were 0.8 cm too low. Conclusion The accuracy of the BoneXpert method in terms of root mean square error was as predicted by the model, i.e. in line with what was observed in the Zurich studies.