Background/Purpose:

Children with one or more subtypes of juvenile idiopathic arthritis, such as enthesitis-related arthritis (ERA), often exhibit growth impairments. The purpose of the analysis was to explore the impact of adalimumab (ADA) on growth in pediatric patients (pts) with ERA.

Methods: Pts aged 6-<18 with ERA were enrolled in a phase 3, multicenter, randomized, double-blind, study. Following 12 weeks of treatment with ADA (24 mg/m² BSA up to 40 mg every other week [eow]) or placebo, pts were eligible to enroll in an open-label extension and receive ADA eow for up to an additional 192 weeks. For this analysis, all pts who received ≥1 dose of ADA were included, and pts were grouped by baseline height percentiles into 2 categories: ≤25^th and >25^th percentiles based on the World Health Organization (WHO) growth charts. Mean WHO percentile changes in height, weight, and body mass index (BMI) percentiles were calculated through 204 weeks. Per protocol, bone age and familial height were not collected. Growth and efficacy data were analyzed as observed.

Results:

Among the 46 pts who received ≥1 dose of ADA in this study, 67% were male with a mean age of 12.9 years; no pts had associated IBD. Eleven pts (24%) were in the ≤25^th height percentile, and these pts had a numerically lower baseline height (147.7 cm) and weight (42.5 kg) compared with those pts who were in the >25^th height percentile (156.0 cm and 51.5 kg, respectively). Additionally, numerically higher proportions of pts in the ≤25^th percentile received concomitant corticosteroids than did the >25^th percentile group (54.5% vs 28.6%). Pts in the ≤25^th percentile group experienced a larger change in mean height percentile through 204 weeks of ADA treatment (70.3 vs 20.5 for the >25^th percentile), a finding that was evident within the first 6 months of treatment. Juvenile males in the ≤25^th baseline height percentile demonstrated the numerically highest rates of growth, although similar levels of growth improvement were observed for the lowest quartile of females as well. None of the 11 pts in the ≤25^th baseline height percentile remained in this category at their final study visit (Table). Similar percentile increases were observed for BMI percentiles between groups. ACR Pedi90 response rates improved over time in both ≤25^th and >25^th percentile groups, reaching approximately 80% at the end of 3 years treatment with ADA.

Conclusion:

Long-term ADA treatment was associated with growth improvement and maintenance in children with ERA. These improvements among children in the lowest WHO quartiles at baseline may improve their quality of life and psychosocial environment. ADA treatment improved ERA signs and symptoms, regardless of baseline growth status.

Reference: ¹Burgos-Vargas R, et al. Arthritis Rheumatol 2016;68(Suppl 10).

Table. Distribution of Height and BMI by WHO Percentile at Baseline and Final Visit

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-impact-of-adalimumab-on-growth-in-patients-with-pediatric-enthesitis-related-arthritis/