Early Inflammatory Markers are Associated With Inadequate Post-Induction Infliximab Trough in Pediatric Crohn's Disease.

OBJECTIVES: In pediatric Crohn's disease, infliximab trough concentrations after standard weight-based induction therapy are commonly below 7 µg/mL. Clinical treatment outcomes are associated with post-induction infliximab trough concentration. Markers of inflammation are associated with low infliximab concentrations during maintenance dosing. We sought to determine if early markers of disease activity are associated with inadequate post-induction infliximab trough concentrations in pediatric Crohn's disease. METHODS: We performed a retrospective single-center case-control study of pediatric Crohn's disease patients to assess the association between baseline and week-2 biomarkers (albumin, C-reactive protein, and erythrocyte sedimentation rate) and inadequate post-induction infliximab trough concentration (<7 µg/mL) in patients treated with standard 5 mg/kg dosing. Baseline and week-2 biomarker values were coded as dichotomous variables at clinically useful thresholds. Univariable logistic regression was used to calculate odds ratios of developing an inadequate infliximab trough concentration for each threshold, as well as thresholds in combination. RESULTS: Fifty-five patients were evaluated. Early biomarker thresholds significantly associated with inadequate post-induction infliximab trough concentrations included baseline C-reactive protein >1 mg/dL (odds ratio [OR] 4.58; 95% confidence interval [CI] 1.24--17.01), both baseline C-reactive protein >0.5 mg/dL and albumin <3.5 g/dL (OR 8.31; 95% CI 1.99--34.63), and week-2 C-reactive protein >0.5 mg/dL or albumin <3.5 mg/dL or erythrocyte sedimentation rate >25 mm/hour (OR 11.08; 95% CI 2.14--57.22). CONCLUSIONS: Routine baseline and week-2 markers of disease activity at clinically useful thresholds were associated with inadequate post-induction infliximab trough concentration in pediatric Crohn's disease patients receiving standard weight-based induction dosing.