ESPE Abstracts

Background: Paediatric growth hormone deficiency (PGHD) is treated with daily somatropin (recombinant human growth hormone) injections. High rates of discontinuation and poor adherence to treatment, which are associated with worse growth outcomes, have been documented previously, for example in the US and EU. Discontinuation of somatropin has not yet been evaluated using real-world data in Japan.

Objectives: To describe discontinuation of, and persistence to, daily somatropin treatment among children with pGHD in Japan.

Methods: This was a retrospective cohort study of children (≥3 and <16 years old) who were prescribed somatropin, using two Japan-based databases, Japan Medical Data Center (JMDC) and Medical Data Vision (MDV). Children were required to have ≥1 prescription for somatropin (first prescription = index date) within each study period (1st January 2002 to 30th June 2021 for JMDC and 1st January 2009 to 31st October 2021 for MDV) and ≥1 GHD diagnosis code without a somatropin prescription during the 6-months pre-index. Children were required to be continuously enrolled in the database ≥6 months preceding and ≥3 months following index date. Children were followed for up to 48 months post-index. Early persistence was defined as proportion of children with >1 refill of somatropin subsequent to the initial prescription. Discontinuation was defined as the first observation of a gap in therapy (using >60 and >90-day gap thresholds) between successive somatropin prescription fill dates. Persistence was defined as continuous refills of somatropin with no gaps in therapy. Time to discontinuation/non-persistence was evaluated using Kaplan Meier methods, and Cox proportional hazards models identified predictors of time to discontinuation.

Results: Among the children included in this study (JMDC n=452, MDV n=573), most were male (JMDC 64.8%, MDV 60.0%). Mean age (standard deviation) was 8.8 years (3.6) in JMDC and 7.5 years (3.6) in MDV. Early persistence was high across both cohorts (JMDC 91.2%, MDV 83.4%). Using the more conservative 90-day gap definition for discontinuation, a sizable proportion of children discontinued over the follow-up period: JMDC 19% at 12 months, 35% at 48 months, and MDV 33% at 12 months, 54% at 48 months. No meaningful predictors of discontinuation were identified.

Conclusions: Despite high early persistence with somatropin, many children with pGHD in Japan were increasingly non-persistent over time: at 48 months post-index, one-third to one-half of children discontinued therapy. These results suggest a need for new strategies to support medication use over time among children with pGHD in Japan.