ESPE Abstracts

Background: Several criteria for growth response to growth hormone (GH) therapy have been developed. These include height velocity (HV), height standard deviation score (HSDS), ΔHV, and ΔHSDS. Other parameters considered as predictors of growth response include age at start, weight SDS, GH dose, and target height SDS. Among these, the two most important parameters to predict future height before treatment start are HSDS and age.

Aim: To develop growth charts with cut-offs for poor growth response using real-world data of patients with growth hormone deficiency (GHD) and those born small for gestational age (SGA).

Methods: GHD and SGA patients aged 2–14 years at treatment start were extracted from the Growzen™ digital health ecosystem. Imputed HSDS were estimated at 3-month intervals between 0-48 months using the broken stick method. HSDS was calculated using country-specific or WHO growth references. GAMLSS distributions by indication were fitted to obtain growth charts of ΔHSDS by HSDS at treatment start for three different age groups: 2─6, 7─9 and 10─14 years. Relative poor growth response was defined as a cut-off of −1.0 SD corresponding to a proportion of 16% (P16).

Results: Height data were available for 3,937 GHD patients with 19,791 height measurements, and 972 SGA patients with 4,630 height measurements. For GHD, −1 SD of ΔHSDS in the first year of treatment ranged between 0.34 (−1.5 HSDS at start) and 0.45 (−3 HSDS at start) when 2−6 years, 0.30-0.41 when 7−9 years, and 0.27-0.37 when 10−14 years of age at treatment start. After 4 years of treatment, these values ranged between 0.81-1.43 when 2−6 years, 0.75-1.33 when 7−9 years, and 0.78-1.32 when 10−14 years of age at treatment start. For SGA, these values were almost similar in the first year. After 4 years, distribution was much wider within the SGA group compared to the GHD group, which resulted in lower cut-off values.

Conclusion: Our results confirm that low HSDS and age at treatment start are associated with better growth response. Moreover, even in instances of late treatment start, there exists a growth response, indicating that age should not be a restrictive factor when considering treatment. The variability in long-term growth response was greater within SGA than in the GHD, which is likely due to heterogeneity of SGA. Healthcare professionals may utilise growth charts with a −1 SD cut-off for poor growth response in the first year for personalising treatment strategies, including adherence and dose management.