Height outcomes in children with growth hormone deficiency and idiopathic short stature treated concomitantly with growth hormone and aromatase inhibitor therapy: data from the ANSWER program

BACKGROUND: Treatment of children with growth hormone deficiency (GHD) or idiopathic short stature (ISS) using GH is only effective for bone growth prior to epiphyseal fusion. Aromatase inhibitor therapy (AIT) blocks estrogen production, thereby delaying epiphyseal fusion. The current study analyzed baseline characteristics and longitudinal data of male patients with GHD or ISS who were treated with GH and concomitant AIT. METHODS: Data were obtained from the observational American Norditropin® Studies: Web-Enabled Research (ANSWER) Program, which collected efficacy and safety data of patients treated with Norditropin®. A longitudinal cohort approach compared patient characteristics, including chronologic age, bone age, and height standard deviation score (HSDS), in GH-treated males before and after AIT initiation. RESULTS: A total of 142 GH-naïve patients with GHD (n = 115) or ISS (n = 27) with mean (± SD) baseline chronological ages of 12.10 ± 3.00 and 10.76 ± 3.07 years, respectively, were analyzed. The majority were classified at advanced Tanner stages II to V. Patients with GHD had mean HSDS of − 1.97 ± 0.78 at baseline and − 0.99 ± 0.88 prior to AIT initiation, while corresponding values for patients with ISS were − 2.15 ± 0.72 and − 1.04 ± 0.79, respectively. In patients evaluated after 2 years of concomitant AIT, mean HSDS had decreased to − 0.40 ± 1.16 and − 0.65 ± 0.52 for patients with GHD and ISS, respectively. Patients with GHD had a mean bone age/chronological age ratio (BA/CA) of 0.91 ± 0.11 at baseline and 0.97 ± 0.10 prior to AIT initiation, while corresponding values for patients with ISS were 0.85 ± 0.16 and 0.99 ± 0.10, respectively. In patients evaluated after 2 years of concomitant AIT, mean BA/CA values were 0.95 ± 0.10 and 0.96 ± 0.06 for patients with GHD and ISS, respectively. CONCLUSIONS: In this real-world analysis, use of AIT with GH in males appeared to be associated with ongoing growth over 2 years, and AIT likely augmented growth potential as indicated by continued HSDS increase with decreased BA/CA after AIT initiation. TRIAL REGISTRATION: This trial was sponsored by Novo Nordisk and is registered with ClinicalTrials.gov (NCT01009905). Registered November 11, 2009; retrospectively registered