Sub-Optimal Adherence With Daily Growth Hormones Increases With Each Year of Treatment in a US Commercial Claims Database
Authors: Loftus Jane , Chen Yong , Alvir Jose Ma J , Chi Lei , Dasgupta Shibasish , Gupta Anu , Wajnrajch Michael P 
Published: May 2021

Abstract
Introduction and Objective: Pediatric growth hormone deficiency (pGHD) occurs in approximately 1 in 4,000 children. The main manifestation is short stature managed with daily injections of somatropin, a recombinant human growth hormone (r-hGH). Prior research has shown that children with good adherence with r-hGH have significantly greater linear growth compared to those with sub-optimal adherence. While previous studies have found sub-optimal adherence with daily r-hGH injectables among children with pGHD, to date, r-hGH adherence has not been studied among large, usual-care populations using validated measurements of adherence. We describe adherence to somatropin treatment over 4 years in a population-based study.
Materials and Methods: A retrospective cohort analysis of commercially insured patients ≥3 and &lt;16 years, diagnosed with pGHD, newly treated with somatropin from 01 January 2002 through 31 December 2019 (study time period) was conducted using Optum De-identified Clinformatics Data Mart database. Index date was defined as the first prescription for somatropin between 01 July 2002 to 30 September 2019. Four patient cohorts were identified (12, 24, 36, and 48 months of post-index continuous enrollment). The demographic and clinical profiles of children with pGHD treated with daily injections of somatropin who have good adherence and those with sub-optimal adherence were characterized. Good adherence was defined as medication possession ratio (MPR) of ≥ 80%, sub-optimal adherence as MPR &lt;80%. Logistic regression models will evaluate the relationship between demographic characteristics (age, gender, race/ethnicity) and adherence (good vs. sub-optimal).
Results: Patient characteristics were similar across each cohort; in the 12-month cohort (n=3091), mean age was 11.34 ±2.89 years, 75.9% were male, 70.9% white, 9.4% Hispanic, 3.6% Asian, and 3.1% black. At 48 months, 1193 (38.6%) of the 12-month cohort remained for follow-up. At 12 months, 80.1% had good adherence and mean (95% CI) MPR was 0.89 (0.88-0.89) while mean (95% CI) MPR at 48 months was 0.82 (0.81-0.83). The proportion with good adherence at months 24, 36, and 48 were 70.2%, 65.6%, and 64.0%, respectively. Adherence was not associated with age or gender. Blacks and Hispanics consistently exhibited lower adherence. At 12 months, good adherence was observed among 85.7% of Asians, 80.0% of whites, 77.2% of Hispanics, and 76.0% of blacks; at 48 months, good adherence was observed among 73.9% of Asians, 65.4% of whites, 56.8% of blacks, and 55.2% of Hispanics. Logistic regression model results will be provided.
Conclusion: Although the majority of children with pGHD demonstrated good adherence with a daily r-hGH regimen, sub-optimal adherence increases with treatment duration and is higher among black and Hispanic children. Strategies that facilitate good adherence to r-hGH may support improved clinical outcomes.