ESPE Abstracts

Background/Aim: Several criteria for the first year growth response (FYGR) to growth hormone (GH) treatment have been proposed. We explored which FYGR criteria predict best the final height outcome after GH treatment in prepubertal children with GH deficiency (GHD).

Methods: Height data of 129 GHD children (83 boys) treated with GH for at least 4 consecutive years with at least 1 year before pubertal onset, were retrieved from the Belgian GH Registry. The FYGR parameters were: (1) increase in height (ΔHt) SDS, (2) height velocity (HV) SDS, (3) ΔHV (cm/year), (4) index of responsiveness (IoR) in KIGS prediction models, (5) first-year HV SDS based on the KIGS expected HV curve (HV KIGS SDS), (6) near final adult height (nFAH) prediction after first-year GH treatment. Poor final height outcome (PFHO) criteria were: (1) nFAH SDS <-2.0, (2) nFAH SDS minus midparental height SDS <-1.3, (3) total ΔHt SDS <1.0. ROC curve analyses were performed to define the optimal cut-off for FYGR parameters. Only ROC curves with an area under the curve (AUC) of more than 70% were further analyzed.

Results: Twenty two, 10 and 12 % of the children had respectively a nFAH SDS <-2, nFAH SDS minus midparental height SDS <-1.3, and total ΔHt SDS <1. The AUC's ranged between 73 and 85 %. The highest AUC was found for first-year ΔHt SDS to predict total ΔHt SDS <1, and predicted nFAH SDS to predict nFAH SDS <-2. Most currently used FYGR criteria had a low specificity and sensitivity to detect a PFHO at their standard cut-off values. ROC curve analyses revealed that to obtain a desired specificity of 95% the cut-off value (and sensitivity) of the FYGR parameters were: ΔHt SDS < 0.35 (40%), HV SDS < -0.85 (43%), ΔHV < 1.3 cm/year (36%), IoR <-1.57 (17%), and HV KIGS SDS <-0.83 (40%) to predict total ΔHt SDS <1; predicted nFAH SDS (with GH peak) < -1.94 (25%), and predicted nFAH SDS (without GH peak) < -2.02 (25%) to predict nFAH SDS < -2. At these cut-offs with 95% specificity the amount of correctly diagnosed poor final responders equals the amount of false positives.

Conclusion: First-year growth response criteria for GH treatment perform poorly as tests to predict a poor final height outcome.