Abstract Background The effectiveness of subcutaneous infliximab (SC-IFX) for managing perianal fistulizing Crohn’s disease (pfCD) has not yet been evaluated. Methods We included adult patients with pfCD receiving SC-IFX who underwent perianal magnetic resonance imaging (pMRI) and serum SC-IFX concentration measurement within one month. Perianal fistula activity was evaluated using the modified Van Assche Index (mVAI); radiologic remission was defined as an mVAI inflammatory subscore of 0. Receiver operating characteristic (ROC) analysis evaluated the SC-IFX threshold associated with remission. Self-controlled before–after analysis using paired t-tests was conducted on patients who underwent pMRI within two years before and after switching to SC-IFX. Results Of 72 patients, 59 (82 %) achieved radiologic fistula remission. Mean SC-IFX concentrations were 22.9 ± 9.3 µg/mL in remitters and 21.5 ± 9.9 µg/mL in non-remitters (p = 0.251). The ROC-derived threshold for radiologic fistula remission was 19.2 µg/mL (area under the curve, 0.61; 95 % confidence interval, 0.42–0.80). In 45 patients with paired MRIs, mVAI decreased significantly after switching (p = 0.037). Among the 15 non-remitters (34.9%) at baseline pMRI, eight patients showed no change in mVAI after switching to SC-IFX, and seven showed decreased mVAI, of whom four achieved radiologic remission. Radiologic fistula remission was observed in 28 patients (65.1%) at baseline pMRI and was maintained in 27 patients, while one patient experienced worsening of mVAI. Conclusion SC-IFX maintained radiologic fistula remission and reducing mVAI in some baseline non-remitters, supporting its real-world effectiveness in pfCD. Conflict of interest: Prof. Hong, Sung Noh: Grants & Consulting : Celltrion Ji Eun, Kim: No conflict of interest Dong Kyung, Chang: No conflict of interest Kim, Young-Ho: No conflict of interest
Hong et al. (Thu,) studied this question.