Clinical performance of an infliximab rapid quantification assay

• Main Author: Magro, Fernando
• Publication Date: 2017
• Other Authors: Afonso, Joana, Lopes, Susana, Coelho, Rosa, Gonçalves, Raquel, Caldeira, Paulo, Lago, Paula, Sousa, Helena Tavares, Ramos, Jaime, Gonçalves, Ana Rita, Ministro, Paula, Rosa, Isadora, Meira, Tania, Andrade, Patrícia, Soares, João-Bruno, Carvalho, Diana, Sousa, Paula, Vieira, Ana Isabel, Lopes, Joanne, Dias, Cláudia Camila, Geboes, Karel, Carneiro, Fátima
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.1/11905
• topic: Inflammatory-bowel-disease; Ulcerative-colitis; Crohns-disease; Serum infliximab; Elisa Kits; Antibodies; Therapy; Optimization; Association; Cohort

Background: Therapeutic drug monitoring (TDM)-based algorithms can be used to guide infliximab (IFX) adjustments in inflammatory bowel disease (IBD) patients. This study aimed to explore a rapid IFX-quantification test from a clinical perspective. Methods: This manuscript describes a prospective cohort study involving 110 ulcerative colitis (UC) patients on the maintenance phase of IFX. IFX trough levels were quantified using a rapid quantification assay and a commonly-used reference kit. Results: Irrespective of the assay used to measure IFX, its through levels were statistically different between patients with and without endoscopic remission (Mayo endoscopic score = 0), as well as between patients stratified by their faecal calprotectin (FC) levels. Despite the fact that the two methods correlated well with each other [Spearman's rank correlation coefficient = 0.843, p < 0.001; intraclass correlation coefficients = 0.857, 95% confidence interval (CI): 0.791-0.903], there was a discernible systematic variation; values obtained with the reference kit were on average 2.62 units higher than those obtained with the rapid assay. Notwithstanding, 3 mu g/ml was shown to be an acceptable cut-off to assess endoscopic status and inflammatory burden levels using both assays. The percentage of patients that had a positive outcome when the IFX concentration measured by the rapid assay ranked above 3 mu g/ml was 88% both for a Mayo endoscopic score <= 1 and for an FC concentration <250 mu g/g. Conclusions: Based on this study, we concluded that using the rapid IFX assessment system with a 3 mu g/ml threshold is a reliable alternative to the time-consuming enzyme-linked immunosorbent assays in patients on the maintenance phase of IFX.