Association of Growth Hormone Adherence and Growth Outcomes in Paediatric Patients: Results From a Clinical Registry

OBJECTIVE: Daily growth hormone (GH) therapy for growth disorders requires long-term adherence. The aim of this study was to investigate the association of adherence with 2-year growth outcomes in paediatric patients receiving daily GH therapy in a clinical registry. DESIGN: Retrospective cohort study. PATIENTS: Patients with growth disorder were categorized after 2 years of treatment into low adherence (< 85%), high adherence (85%-110%) and adherence > 110% groups. Only patients with consistent adherence classification across both years were included in the 2-year outcome analysis. MEASUREMENTS: Growth outcomes were compared the change in height standard deviation score (ΔHSDS) over 2 years. Statistical tests were performed using the nonparametric Spearman's rank correlation coefficient and a general linear regression model. RESULTS: Seventy-four patients were analysed after 2 years of treatment. Mean ΔHSDS was 0.87 in the high adherence group and 0.33 in the low adherence group (absolute difference 0.54). Using the Spearman's correlation coefficient, ΔHSDS was statistically significantly positively correlated with high adherence compared to low adherence (rs = 0.33; p < 0.01). The linear regression results support these findings and estimate an improved ΔHSDS of 0.44 for patients in the high adherence group compared to the low adherence group (p = 0.03). Mean ΔHSDS in the adherence > 110% group was 0.79. CONCLUSION: Sustained high adherence (≥ 85%) to daily GH therapy was associated with clinically meaningful improvement in growth over 2 years.