P734 Should we have a higher threshold for anti-TNF serum levels in Crohn’s disease patients with perianal disease?

Abstract

Abstract Background Tumour necrosis factor (TNF) inhibitors are potent drugs effective for the treatment of both luminal disease and perianal fistulas in Crohn’s disease (CD). Recently, there is some evidence that patients with perianal disease might need higher concentrations of anti-TNF levels compared with patients without perianal disease. The aim of this study was to compare anti-TNF serum concentrations: IFX (infliximab) or ADA (adalimumab) between patients with active and closed perianal fistulas with CD. Methods Retrospective study including that was on anti-TNF for at least 6 months. Fistula closure was defined as absence of active drainage at gentle finger compression and/or fistula healing on magnetic resonance imaging/ultrasound. Results We included 55 patients with CD and perianal disease, 54.5% males, median age of 31 (interquartile range: 18–71) years. Forty-two were on IFX and 13 on ADA. Median IFX serum concentrations [IQR] were higher in patients with closed fistulas (n = 19) compared with patients with actively draining fistulas (n = 23): 7.7 mg/ml [0–32.6] vs. 1.5 mg/ml [0–9.5], respectively (p < 0.001). A similar difference was seen in patients treated with ADA: median serum concentrations were 9.6 mg/ml [6–21.9] in 10 patients with closed fistulas vs. 4 mg/ml [4–4.3] in 3 patients with producing fistulas, p = 0.007. Serum concentrations superior or equal to 4.68 mg/ml for IFX (AUC of 0.87; 95% CI: 0.73–0.96) were associated with fistula closure. Conclusion Higher serum levels of anti-TNF drugs were associated with perianal fistula closure. Patients with CD and perianal disease may benefit from intensification of biological therapy.