Supplementary Material for: A growth prediction model from mid-puberty to near adult height in adolescents with idiopathic isolated growth hormone deficiency treated with growth hormone

Introduction Recombinant human growth hormone (rhGH) treatment of children with idiopathic isolated growth hormone deficiency (IIGHD) typically results in catch-up growth for several years followed by a period of normal growth. The effect of rhGH treatment on late pubertal height gain in adolescents with IIGHD has remained unclear. This study aimed to develop and validate a prediction model for height gain from mid-puberty to near adult height (NAH) in patients with IIGHD, treated with rhGH. Methods Data from the Dutch National Registry of Growth Hormone Treatment in Children were used, focusing on 151 patients who received rhGH treatment until NAH. Predictors included age, bone age, Tanner stage, and target height SDS minus height SDS at mid-puberty. Validation was performed in 33 males and 7 females who had a normal GH response in a GH stimulation test at mid puberty and continued rhGH until NAH. Results The model explained 48% of the variance for males (residual SD 4.16 cm) and 18% for females (residual SD 3.64 cm). Validation showed a mean (SD) difference of 1.48 (2.36) cm for males and 3.57 (2.66) cm for females between predicted and attained NAH. Conclusion For females, explained variance was insufficient to reliably predict height gain. For GH sufficient males, the model can be used to assess efficacy of continuing or discontinuing rhGH treatment at mid-puberty in future studies.