OBJECTIVES: Adherence to growth hormone (GH) therapy has been reported suboptimal in a large proportion of paediatric patients, which can lead to suboptimal clinical outcomes. We aimed to characterize and to analyse adherence and treatment duration with GH therapy, through National Health Service (NHS) Hospital electronic prescription databases.

METHODS: This was a study based on data from electronic prescription databases of 9 NHS Hospitals, in the period from 2011 to 2020. We included patients under 18 years and with at least one dispensed prescription registry of GH therapy. For adherence and treatment duration analysis, we selected data from newly treated patients (index prescription registry date defined as the first dispensed prescription registry three months after the start of each Hospital database). Good adherence was defined as continuous measure of adherence (CMA) of ≥ 80% and sub-optimal adherence as CMA < 80%. Treatment duration was estimated using Kaplan-Meier survival curves.

RESULTS: Overall, 1.272 patients were included (male 62%). Average age at their first dispensed prescription registry was 10,5 years. Across newly medicated patients (n=738), average treatment duration was 5 years (a minimum of 1 month on GH therapy and a maximum of approximately 9 years). 53% of the entire population presented a CMA of ≥ 80%. Those not achieving the 80% landmark also had a relatively high CMA, with the populational average achieving 79%. CMA increased over the years (CMA was 71% after 1 year of treatment, 79% after 3 years and 93% after 9 years). Kaplan Meier analysis curve showed that 11,3% of patients will remain on treatment for 9 years.

CONCLUSIONS: This study provided real-world adherence to GH therapy estimate in a Portuguese paediatric population. About half of the children presented a good adherence to treatment. Adherence increased with therapy duration, attaining 93% after 9 years of treatment.