Suboptimal adherence to daily growth hormone in a US real-world study: an unmet need in the treatment of pediatric growth hormone deficiency

Abstract

Objective To evaluate adherence to, and discontinuation of, somatropin treatment over 4 years in a US population-based study of children with pediatric growth hormone deficiency (pGHD). Methods A retrospective cohort analysis of commercially insured patients ≥3 and <16 years, diagnosed with pGHD, newly treated with somatropin was conducted using Optum De-identified Clinformatics Data Mart. Index date was defined as the first prescription for somatropin between 01 July 2002 and 30 September 2019. Five non-exclusive patient cohorts were identified (>3, 12, 24, 36, and 48 months of post-index continuous enrollment). Suboptimal adherence was defined as medication possession ratio <80%. Discontinuation was defined as the date at which a gap of >60 days between somatropin fills first occurred. Cox proportional hazards regression was used to evaluate time to discontinuation. Results In the 12-month cohort (n = 3091), mean age was 11.3 ± 2.9 years, 75.9% were male, 70.9% white, 9.4% Hispanic, 3.6% Asian, and 3.1% black. The proportion with suboptimal adherence at months 12 and 48 was 19.6% and 35.9%, respectively. Discontinuation occurred in 42.2% of patients. The rate of discontinuation (HR [95% CI]) was higher for age ≥10 (1.74 [1.53–1.98]), females (1.35 [1.21–1.50]), black and Hispanic race/ethnicity (1.50 [1.18–1.90] and 1.27 [1.09–1.49] compared to White) and obesity (1.69 [1.19–2.40]). Conclusion Suboptimal adherence increases with treatment duration, and risk of discontinuation is associated with age, female gender, black or Hispanic race/ethnicity, and obesity. Strategies that facilitate adherence among children at risk of discontinuation may improve clinical outcomes.