Growth hormone regimens in Australia: Analysis of the first 3 years of treatment for idiopathic growth hormone deficiency and idiopathic short stature

Abstract

Objective: To investigate response to growth hormone (GH) in the first, second and third years of treatment for all idiopathic GH-deficient (GHD) and idiopathic short stature (ISS) patients in Australia. Context: Eligibility for subsidized GH treatment in Australia is determined on auxological criteria for the indication of Short Stature and Slow Growth (SSSG), which includes ISS (SSSG-ISS). The biochemical GHD (BGHD, peak GH < 10 mU/l) and SSSG indications are treated similarly: starting dose of 4.5 mg/m 2/week with provision for incremental dosing. Some ISS patients were specifically diagnosed with familial short stature (SSSG-FSS). Design: Responses for each year of treatment for BGHD, SSSG-ISS and SSSG-FSS cohorts were compared in relation to influencing variables and with international benchmarks. The effect of incremental dosing was assessed. Patients: Australian BGHD, SSSG-ISS and SSSG-FSS patients who had completed 1, 2, or 3 years of treatment and were currently receiving GH. Measurements: Growth hormone dose, change in height-standard deviation score (ΔSDS) and growth velocity (GV). Results: First-year response was 2-3 times greater than that in subsequent years: ΔSDS 1st year = 0.92, 0.50 and 0.46 for BGHD, SSSG-ISS and SSSG-FSS, respectively. Responses were similar to international reports and inversely related to age at commencement of GH. First-year GV-for-age for BGHD patients was similar to international standards for idiopathic GHD. However, girls had an inferior response to boys when treatment commenced at <6 years of age. First-year GV-for-age for SSSG-ISS/FSS patients was less than ISS standards. Dose increments attenuated the first-to second-year decline in response to BGHD but marginally improved the responses for SSSG-ISS/FSS. Conclusions: The Australian auxology-based GH programme produces comparable responses to international programmes. A lower starting dose is offset by the initiation of treatment at younger ages. Incremental dosing does not appear optimal. A first-year dose of 6.4-6.9 mg/m 2/week for GHD and 8.9 mg/m 2/week for ISS with early commencement of GH treatment may be most efficacious. © 2012 Blackwell Publishing Ltd.