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

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 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.