Trough serum infliximab: a predictive factor of clinical outcome for infliximab treatment in XXXX .

@entity1 @entity31
BACKGROUND AND AIMS: Antibodies to infliximab reduce serum infliximab with loss of clinical benefit, but undetectable trough serum concentrations of infliximab may occur without antibody formation. The relationship between trough serum infliximab and clinical outcomes was evaluated in @entity31 . METHODS: In a cohort of 115 @entity1 with @entity31 treated with three-dose induction followed by scheduled maintenance infliximab, rates of clinical remission, colectomy, antibodies to infliximab and trough serum infliximab were determined. RESULTS: Rates of remission were 32% at week 10 and 37% at week 54. Colectomy occurred in 40% of @entity1 , at a median of 5.3 (IQR 1.9-12.1) months. Detectable trough serum infliximab was present in 39% of @entity1 and, among @entity1 with undetectable infliximab, 41% were antibody positive and 20% were antibody negative. For antibody-positive and antibody-negative @entity1 , rates of remission (18% vs 14%), endoscopic improvement (25% vs 35%) and colectomy (52% vs 59%) were not different. A detectable serum infliximab was associated with higher rates of remission (69% vs 15%; p<0.001) and endoscopic improvement (76% vs 28%, p<0.001). An undetectable serum infliximab predicted an increased risk for colectomy (55% vs 7%, OR 9.3; 95% CI 2.9 to 29.9; p<0.001). Concurrent immunosuppression was not associated with clinical outcomes. CONCLUSIONS: For @entity1 with @entity31 treated with infliximab, a detectable trough serum infliximab predicts clinical remission, endoscopic improvement and a lower risk for colectomy. An undetectable trough serum infliximab, irrespective of antibody status, is associated with less favourable outcomes.
