ESPE Abstracts

Background and Objective: The American Norditropin Studies: Web-Enabled Research (ANSWER) Program is a long-term, US-based, non-interventional study designed to collect information on the effectiveness and safety of Norditropin^® growth hormone (GH). From June 2002 to September 2016, 20,204 pediatric patients were enrolled by their treating physicians, including 1,003 patients with Turner syndrome (TS). This analysis compares cumulative GH doses when adjusting GH dosage based on body weight (BW; actual dosing) vs body surface area (BSA; theoretical dosing calculated from average BSA and average dose).

Methods: Patient information was entered by participating physicians using a web-based tool. A total of 577 eligible TS patients were GH-naïve at study entry. The theoretical BSA-based dose of 1.46 mg/day was derived from observed dose vs BSA data that best corresponded with an ideal body weight (BSA=1 m²).

Results: Patients with TS (n=577) had a mean (SD) baseline height standard deviation score (SDS) of -2.52 (1.02), baseline weight SDS of -1.16 (1.45), and baseline insulin-like growth factor-I (IGF-I) SDS of -0.66 (1.72); mean (SD) and median start age for GH treatment were 9.25 (3.95) and 9.56 years, respectively. At baseline, 338 patients (59%) were aged <10 years, and 239 (41%) were ≥10 years; spontaneous puberty (Tanner stage ≥ 2) was reported for 23 patients. After starting GH treatment, mean IGF-I SDS increased from baseline (-0.66) to year 1 (+1.11), and then remained similar during further treatment follow-up. The ratio of BW-based vs theoretical BSA-based GH dose (1.46 mg/day) was <1 before age 10 years and >1 after age 10 years. Compared with BSA-based dosing, mean GH dose with BW-based dosing was lower before age 10 years, but higher after age 10 years.

Conclusions: GH dosing based on a hybrid method in which the GH dose is BW-based before age 10 years and BSA-based after age 10 years may result in a lower cumulative dose than BW-based GH dosing alone. Conclusions regarding the effectiveness of BSA-based dosing could not be derived from these retrospective data, as all BSA-based doses were theoretical; however, demonstrating the effectiveness of a hybrid dosing method may support a rationale for optimized and individualized GH dosing and could have the potential to lower the cost of therapy. Further research is warranted to explore the benefits of a hybrid dosing method and whether this approach results in height outcomes similar to those of BW-based dosing.