Association of Daily Growth Hormone Injection Adherence and Height Among Children With Growth Hormone Deficiency

Abstract

ObjectiveRecombinant human growth hormone (somatropin) is recommended for children with growth hormone deficiency (GHD) to normalize adult height. Prior research has indicated an association between adherence to somatropin and height velocity. Further research is needed using real-world data to quantify this relationship; hence the objective of this study was to investigate the association between adherence to somatropin and change in height among children with GHD. MethodsThis retrospective cohort study included patients in the IQVIA PharMetrics Plus and Ambulatory Electronic Medical Records databases aged 3 to 15 years, with ≥1 GHD diagnosis code claim and newly initiated on somatropin between January 1, 2007 and November 30, 2019. Adherence was measured over the follow-up using the medication possession ratio (MPR); patients were classified as adherent (MPR ≥ 0.8) or nonadherent (MPR < 0.8). ResultsAmong 201 patients initiated on somatropin, 74.6% were male, mean age was 11.4 years, and the mean follow-up was 343.3 days. Approximately 76.6% of patients were adherent to somatropin over the follow-up period. Adjusted growth trajectories were similar between adherent and nonadherent patients pre-treatment initiation (P = .15). Growth trajectories post-initiation were significantly different (P = .001). On average, adherent patients gained an additional 1.8 cm over 1 year compared with nonadherent patients, adjusted for covariates. ConclusionGreater adherence to somatropin therapy is associated with improved height velocity. As suboptimal adherence to daily somatropin therapy is an issue for children with GHD, novel strategies to improve adherence may improve growth outcomes.