Persistence with daily growth hormone among children and adolescents with growth hormone deficiency in the UK

BACKGROUND: Children with growth hormone deficiency (GHD) are treated with daily somatropin injections; however, poor treatment persistence and adherence have been recognized previously and have been shown to negatively impact growth outcomes. A recent real-world study of a US pediatric GHD population found that a substantial proportion of children discontinued somatropin therapy, but similar data for a real-world UK population are lacking. OBJECTIVES: To describe the discontinuation of, and persistence with, daily somatropin treatment among children with GHD in the UK. METHODS: This was a retrospective cohort study of children (≥3 and <16 years old) with ≥1 medication prescription for daily injectable somatropin from 1 July 2000 to 31 December 2020 in the IQVIA Medical Research DATA (IMRD) database. Early persistence was defined as the proportion of children prescribed ≥1 somatropin refill (≥2 prescriptions). Discontinuation was defined as the first date at which a medication gap for somatropin (of >60 or >90 days between prescriptions) occurred. Kaplan–Meier methods were used to evaluate persistence (non-discontinuation) over time to assess time to first discontinuation event. Cox proportional hazards models were used to evaluate the relationship between patient characteristics and time to medication discontinuation. RESULTS: Among the cohort identified in this study (n = 117), the majority (n = 84, 71.8%) had 48 months of available follow-up; 56.4% were boys and the mean (median) age was 8.6 (8.0) years. About 98% exhibited early persistence, but persistence over the follow-up period decreased with follow-up duration. Using the conservative 90-day gap definition of persistence, an estimated 72.4%, 52.8%, and 43.3% were persistent at 12, 36, and 48 months. Lower persistence rates were observed using the 60-day definition. No significant patient predictors of time to discontinuation were identified. CONCLUSIONS: Despite high early persistence with somatropin, a high percentage of children with GHD were increasingly non-persistent over time. More than 1 in 4 were non-persistent at 12 months and more than 1 in 2 were non-persistent at 48 months of follow-up. These results suggest that strategies to support improved medication-taking behavior among children with GHD in the UK are warranted.