“Treatment of pediatric growth hormone deficiency (pGHD) involves daily injections of somatropin, a recombinant human growth hormone (r-hGH), administered subcutaneously,” explained the authors of a study published in Current Medical Research and Opinion. “However, adherence to somatropin in real-world settings has been shown to be suboptimal over time among some children with pGHD, primarily attributable to the need for daily injections. Nonadherence with GH treatment, generally defined as more than one missed dose weekly, has been estimated as high as 36%-49%, and non-persistence, or discontinuation of therapy for 1 month or more, has been estimated to occur among approximately 25% of children and 33% of adolescents treated with GH.”
The researchers evaluated adherence to, and discontinuation of, somatropin treatment throughout 4 years in a United States population-based study of children with pGHD. They conducted a retrospective cohort analysis of commercially insured patients aged 3 and older and younger than 16 who were newly treated with somatropin. Index date was defined as the first prescription for somatropin between July 1, 2002 and September 30, 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 less than 80%. Discontinuation was defined as the date at which a gap of more than 60 days between somatropin fills first occurred. Cox proportional hazards regression was used to evaluate time to discontinuation. Within the 12-month cohort (n = 3,091), 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.
Race, Sex & Age Affect Suboptimal Adherence
The study team found that suboptimal adherence to somatropin among children with pGHD increases over time, with more than one in three children exhibiting suboptimal adherence by 48 months following the initiation of somatropin therapy. The proportions with suboptimal adherence at months 12 and 48 were 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 and older (1.74 [1.53–1.98]), females (1.35 [1.21–1.50]), Black and Hispanic races (1.50 [1.18–1.90] and 1.27 [1.09–1.49] compared with White) and those with obesity (1.69 [1.19–2.40]).
“Strategies that facilitate adherence to r-hGH, such as long-acting injectable GH formulations administered weekly, may support improved clinical outcomes,” the study authors wrote. “Furthermore, initiatives tailored to specific patient subgroups who are at risk of suboptimal adherence and discontinuation could help to improve patient care and pGHD outcomes among these populations.”