RESUMO
OBJECTIVES: We evaluated the relationship between serum concentration and efficacy of adalimumab (ADA), an anti-tumor necrosis factor-alpha agent, in pediatric patients with inflammatory bowel disease (PIBD). MATERIALS AND METHODS: This retrospective cross-sectional study traced 75 patients with PIBD (Crohn's disease, n = 57) treated with ADA at two tertiary centers in Finland in 2012-2018. Drug levels and drug antibody titers were chart-reviewed, and the treatment continuation rate of ADA therapy was evaluated. We also assessed the impact of trough levels in the first 3 months on the continuation of ADA within one year of therapy. RESULTS: ADA was introduced at a median age of 13.4 years, and the median disease duration was 2.7 years. During the first year, 22 patients (29%) discontinued ADA due to either loss of response (20%, n = 15) or anti-drug antibody formation (5.3%, n = 4). Regarding trough levels in the first 3 months, 9/16 patients (56%) with trough levels <5 mg/L and 12/20 (60%) with trough levels <7.5 mg/L at 3 months discontinued the therapy by the end of the first year. In comparison, only 8/32 patients (25%) with trough levels >7.5 mg/L at 3 months discontinued treatment during the first year (p = .005). At the last follow-up (median 1.5 years), 52% of the 75 patients were on maintenance therapy and had a median trough level of 8.8 mg/L. CONCLUSION: Higher trough levels in the first 3 months of adalimumab treatment are associated with lower rates of discontinuation due to loss of response during the first year.