Suboptimal adherence to prescribed daily growth hormone regimen among medicaid beneficiaries in the United States.

Objective: The objective of this retrospective cohort study was to describe the adherence and discontinuation patterns of somatropin over 3 years among children with pGHD insured by Medicaid across the United States.

Methods: Eligible children were aged ≥3 and <16 years with Medicaid coverage, diagnosed with pGHD, and had ≥2 new prescriptions for somatropin between 1 July 2014 and 31 December 2018. Four non-exclusive patient cohorts were constructed (≥3, 12, 24, and 36 months of continuous enrollment after initial prescription). Suboptimal adherence was defined as medication possession ratio <0.80, and discontinuation as a gap of >60 days between somatropin fills. Logistic and proportional hazards regression methods were used to estimate odds of suboptimal adherence and time to discontinuation, respectively.

Results: In the 12-month cohort ( = 3623), mean age was 10.5 ± 3.2 years, 70.8% were male, 44.4% White, 29.1% Hispanic, 7.1% Black, and 1.7% Asian. At months 12, 24, and 36, the proportion with suboptimal adherence was 40.9, 50.4, 54.4%, respectively, and 49.2% of patients with ≥3 months of follow-up discontinued therapy. At 12 months, lower age and race/ethnicity (Black vs. White referent) had greater odds of suboptimal adherence. Discontinuation was associated with Black (vs. White referent) race and geographic region.

Conclusions: Sociodemographic characteristics may be risk factors for suboptimal adherence and/or discontinuation of prescribed somatropin therapy. Improving GH regimen adherence among this at-risk population, and specifically among subgroups at highest risk, is warranted to improve clinical outcomes.