P933 Closing the internal opening with a rectal advancement flap increases the effectiveness of mesenchymal stem cell (MSC) injection in the treatment of complex Crohn's disease anal fistulas

Abstract

Abstract Background The injection of MSCs into complex anoperineal fistulas of Crohn's disease gives a combined clinical and radiological remission of between 35 and 50% at 12 months. In our department, surgical closure is now done by rectal advancement flap (and no longer with simple stitches) in order to minimize the passage of stools and contamination of the fistula tract. The aim of this study was to compare the remission rate and the quality of life between patients treated with MSC injection using simple stitches versus a rectal flap to close the internal opening. Methods This single-center prospective study included all our consecutive patients who had a MSC injection. The first patients of the series who had closure of the internal opening(s) with stitches (2020- 2022) were compared with those who had a flap (2022-2023). Complete clinical remission was defined by complete closure of the external opening(s) without pain or discharge, and complete radiological remission by a Magnifi-CD score equal to 0 (Hindryckx P, et al. Gastroenterology 2019). Quality of Life was assessed by the Crohn's Anal Fistula Quality of Life scale (CAF-QoL) (Adegbola SO, et al. Gut 2021). Results We included 68 patients (50% women, mean age: 38 ± 13.8 years). The first 42 had stitches and the following 20 had an advancement flap (6 patients had no procedure due to an anal stenosis). The median follow-up was 12 months [6-24]. The overall complete clinical remission was 66.7% at M12: 51.1% [35.5-66.8] in the "stitches" group versus 87.5% [69.7-100.0] in the "flap" group (p = 0.005) (Figure). The difference was noticed early from M1. The mean overall Magnifi-CD MRI score decreased from 15.5 ± 4.7 to 6.5 ± 7.1 at M12 (p < 0.001) with no difference between the 2 groups. However, more patients in the flap group had a Magnifi-CD score of 0: 62.5% versus 38.2%. The CAF-QoL quality of life score improved from 51.3 ± 24.7 to 21.2 ± 20.8 at M12 (p < 0.001) with no significant difference between the 2 groups. The duration of the procedure was longer on average by 19 ± 7 minutes in the "flap" group. There was no difference in the anal incontinence score between the 2 groups. In logistic regression, the advancement flap was significantly associated with complete clinical remission (p = 0.007, HR (95% CI): 2.3 [1.3-4.3]). Conclusion Closing the internal opening with a rectal advancement flap improves the effectiveness of MSC injections with a complete clinical and radiological remission rate of 87.5% and 62.5% respectively, without consequences on anal continence.