P676 Faecal monitoring is useful in monitoring treatment response in anti-TNF-treated patients

Abstract

Abstract Background Faecal drug concentration is not routinely measured as per therapeutic drug monitoring strategies in inflammatory bowel disease (IBD) patients receiving anti-TNF therapy. However, our previous research work suggested the importance of faecal drug monitoring of anti-TNF agents since active disease may be present in spite of normal serum anti-TNF levels. The aim of the present study was to examine the correlation between faecal calprotectin and faecal infliximab (IFX) concentration and to evaluate the cut-off value of faecal drug concentration in the respect of faecal calprotectin in patients treated with maintenance IFX therapy. Methods Consecutive patients with IBD receiving maintenance IFX therapy at 1st Department of Medicine, University of Szeged were enrolled in the present study. Faecal samples were obtained before the subsequent IFX infusion. Faecal calprotectin and IFX concentrations were determined with ELISA. The correlation between faecal calprotectin and faecal IFX concentration was statistically assessed. Results Sixty-seven IBD patients were enrolled. Female/male ratio was 49%–51%. Sixty-five point six% of the patients were diagnosed with Crohn’s disease and 34.3% with ulcerative colitis. Mean disease duration was 14.9 years (SD 9.7) at the time of analysis. Mean duration of IFX therapy was 42.3 month (SD 31.6). Twenty-eight point three% of the patients received escalated IFX therapy. Mean faecal calprotectin concentration was 545.7 µg/g (SD 379.4 µg/g). Mean faecal IFX concentration was 1 ng/ml (SD 1.3). Faecal calprotectin and faecal IFX concentration showed significant correlation (r=0.37, p = 0.002). A cut-off value of faecal IFX level of 0.6 ng/ml was determined at faecal calprotectin concentration of 500 µg/g. Conclusion According to our results IFX is detectable in the faeces at a calprotectin concentration of 500 µg/g. The cut-off value for faecal IFX concentration proved to be 0.6 ng/ml. Simultaneous determination of faecal anti-TNF and faecal calprotectin concentration is supposed to have a higher benefit in the evaluation of response to IFX therapy.