Performance of new MRI scores: the modified Van Assche Index and the MAGNIFI-CD in the evaluation of the response to anti-TNF in anoperineal fistulas in Crohn's disease

Abstract Background Despite considerable therapeutic advances over the last two decades in the management of Crohn’s disease(CD), complex anoperineal fistulas(APF) still constitute a real therapeutic challenge for the practitioner. Treatment is mainly medico-surgical, combining seton drainage and biotherapy. The ultimate goal is to obtain a deep remission, which combines clinical remission and a normal perineal MRI. Thus, several MRI scores have been proposed to assess the therapeutic response of APF to biotherapy. The aim of this study was to investigate the reliability of the new MRI scores: the modified Van Assche Index(mVAI) and the MAGNIFI-CD in the evaluation of the response of APF to anti-TNFα, by comparing them to the old version of the Van Assche Index(VAI). Methods We conducted a retrospective study, including all patients followed up for CD with APF treated with anti-TNFα over a, 10-year period [2010–2020]. Clinical, biological, morphological and evolutionary data were collected. VAI, mVAI and MAGNIFI-CD scores were calculated from data provided by perineal MRI: number, locations, extensions and lengths of fistulous tracts, characteristics of collections. Clinical response to anti-TNFα was assessed by proctological examination, at the end of which the patients were classified into two groups: • Responders(26): having a complete remission (closure of all initially productive fistulous orifices) or partial response (closure of more than, 50% of orifices) • Non-responders(12): closure of less than, 50% of the initially productive fistulous orifices A statistical study was carried out to compare the performance of the different scores in assessing the response to treatment by calculating the area under the ROC curve with a, 95% confidence interval. Results A total of, 38 patients were included. The mean age was, 42 years [26–73] and the sex-ratio M/F was, 0,4. All patients had received anti-TNFα after disappearance of perineal collections if initially present (Infliximab in, 35 cases(92,1%) and Adalimumab in, 3 cases(7,9%)) combined with thiopurines in, 97,4%. The average duration of anti-TNFα therapy was, 46 months [5–180] The means of the different scores were calculated in responders and non-responders before and after anti-TNFα treatment respectively: A decrease in all three scores was observed after anti-TNFα treatment in the responders, in contrast to the non-responders, thus confirming therapeutic failure. Furthermore, the AUROC of the VAI, mVAI and MAGNIFI-CD scores in the assessment of response to anti-TNFα in APF were, 0,925, 0,908 and, 0,869 respectively. Conclusion Our results suggest that the old version of the VAI, as well as the mVAI and MAGNIFI-CD, are reliable scores with comparable performance in the assessment of response to treatment in APF in CD.