PRELIMINARY VALIDATION OF A PREDICTION MODEL FOR THE SHORT-TERM GROWTH-RESPONSE TO GROWTH-HORMONE THERAPY IN CHILDREN WITH IDIOPATHIC SHORTSTATURE

A discriminant scoring system, using multivariate analysis, has been d eveloped for pretreatment prediction of responsiveness to a 6-month tr ial of growth hormone (GH) treatment in short children with subnormal growth velocity, but without GH deficiency. Inclusion criteria include d a birth weight above 2.5 kg, height below the 3rd centile for chrono logical age, height velocity below the 25th centile for bone age, no s igns of puberty, a maximal GH response to pharmacological stimulation of above 10 mu g/l and treatment with GH at a dose of 12-16 IU/m(2)/we ek. Children with an increase in height velocity greater than 2.5 cm/y ear after therapy were considered to be responders. Pretreatment clini cal data from 67 patients were employed in a discriminant analysis in order to establish the model. The scoring system developed was as foll ows: score = -0.4 + 0.92X(1) - 0.87X(2), where X(1) is the height velo city SD score (SDS) for chronological age, and X(2) is the bone age SD S for chronological age. This model had a specificity of 96.3% and a s ensitivity of 92.5% in predicting the responsiveness to GH. The model has subsequently been applied to a group of 14 patients in order to es tablish its validity; in this group its sensitivity was 83.3% and its specificity 100%. These preliminary data suggest that the model can be used as a guideline for selecting short, slowly growing, non-GH-defic ient children who will respond to short-term GH therapy.