Early growth hormone treatment start in childhood growth hormone deficiency improves near adult height: analysis from NordiNet® International Outcome Study

OBJECTIVE: To investigate the effect of age at growth hormone (GH) treatment start on near adult height (NAH) in children with isolated GH deficiency (GHD). DESIGN: NordiNet® International Outcome Study (IOS) (Nbib960128), a non-interventional, multicentre study, evaluates the long-term effectiveness and safety of Norditropin® (somatropin) (Novo Nordisk A/S) in the real-life clinical setting. METHODS: Patients (n = 172) treated to NAH (height at ≥18 years, or height velocity <2 cm/year at ≥16 (boys) or ≥15 (girls) years) were grouped by age (years) at treatment start (early (girls, <8; boys, <9), intermediate (girls, 8–10; boys, 9–11) or late (girls, >10; boys, >11)) and GHD severity (<3 ng/mL or 3 to ≤10 ng/mL). Multiple regression analysis was used to evaluate the effect of age at treatment start (as a categorical and continuous variable) on NAH standard deviation score (SDS). RESULTS: Age at treatment start had a marked effect on NAH SDS; NAH SDS achieved by patients starting treatment early (n = 40 (boys, 70.0%); least squares mean (standard error) −0.76 (0.14)) exceeded that achieved by those starting later (intermediate, n = 42 (boys, 57.1%); −1.14 (0.15); late, n = 90 (boys, 68.9%); −1.21 (0.10)). Multiple regression analysis showed a significant association between NAH SDS and age at treatment start (P < 0.0242), baseline height SDS (HSDS) (P < 0.0001), target HSDS (P < 0.0001), and GHD severity (P = 0.0012). Most (78.5%) patients achieved a normal NAH irrespective of age at treatment start. CONCLUSIONS: Early initiation of GH treatment in children with isolated GHD improves their chance of achieving their genetic height potential.