Comparison of height for age and height for bone age with and without adjustment for target height in pediatric patients with CF

BackgroundHeight is a strong prognostic factor in cystic fibrosis (CF) and is usually compared to reference values of healthy children by expressing height as a z-score height-for-age (HFA). However, HFA does not take into account a potential delay in bone age (BA) and the genetic potential of the child and could therefore result in misclassification of short stature.MethodsIn 169 children with CF height, BA and target height (TH) were assessed. HFA, height for bone age (HBA), HFA adjusted for target height (HFA/TH) and HBA adjusted for target height (HFA/TH) were determined and children were categorized according to these four methods.ResultsMean z-scores of the four methods ranged from − 0.1 ± 0.8 (HBA/TH) to − 0.5 ± 1.0 (HFA). Prevalence of short stature (z-score <−2 SD) determined by HFA (8%, n = 14) was higher than when HBA, HFA/TH (both 5%, n = 8) and HBA/TH (1% n = 1) were applied.ConclusionThe method used to classify height affects outcome on a group level and for individual patients. Target height and bone age are likely to have added value in the interpretation of height in patients with CF.