Background: Platelet-rich stroma (PRS), a combination of stromal vascular fraction and platelet-rich plasma, proved to be safe and feasible for the treatment of treatment-refractory perianal fistulizing Crohn’s disease (pCD). This study aimed to assess the long-term outcomes in patients with pCD treated with PRS.

Methods: Long term results from adult patients with pCD, who underwent fistula curettage, closure of the internal fistula opening and PRS injection, included in an earlier conducted pilot study (n=25) were assessed up to October 2023. The primary outcome was complete clinical closure at long-term follow-up (closure of all treated external opening[s]). Secondary outcomes comprised complete radiologic closure (absence of fluid-containing tracts on MRI), partial clinical closure (closure of ≥ 1 treated external opening[s]), recurrence (reopening of the external opening after complete clinical and/or radiological closure) and the need for unplanned re-intervention(s).

Results: The majority of the patients was female (56.0%)(mean age 34.4 years [SD: 0.9], and mean follow-up 3.7 years [SD: 0.6])(Table 1). 68% of the patients were concomitantly treated with a biological. During follow-up, ≥1 unplanned re-intervention(s) were necessary in 44% of the patients which were minor (e.g. incision and drainage) in the vast majority (83%)(Table 2). Complete clinical closure at long-term follow-up was reached in 88%. Complete radiologic closure was reached in 75% of patients. Partial clinical closure was reached in all patients (100%). Recurrence was reported in 8% of patients, all whom reached (partial/complete) clinical closure, whereas no recurrence was experienced in patients with complete closure on MRI. All patients with complete radiologic closure achieved clinical closure. Vice versa, patients with clinical closure achieved complete radiologic closure in 82% of the cases.

Conclusion: In this pilot study with treatment-refractory pCD patients treated in a tertiary referral center, all patients had benefit from surgical treatment and additional PRS injection. At long-term follow-up, treatment with PRS injection during surgery is promising as complete clinical and radiological closure is achieved in the majority of these patients. In addition, complete radiologic closure seems a valuable prognostic parameter for long-term success for fistula closure. Future (randomized) research is warranted to further assess the effectiveness of PRS in patients with pCD.

Michiel Bak

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