{
  "abstract": "Background and aims Perianal fistulising Crohn’s disease (pfCD) is an aggressive, disabling condition with significant treatment challenges. The novel TOpClass classification system aims to better capture pfCD’s disease trajectory, improving prognostication and therapeutic decision-making compared with traditional anatomical classifications. This retrospective, multicentre study aimed to provide functional validation of TOpClass and evaluate its clinical applicability in managing pfCD.Methods Data from eight expert centres included 112 patients with 10 years of follow-up. The study assessed transitions between TOpClass classifications in consecutive patients with Crohn’s disease (CD) and active perianal fistulas.Results Most patients (72%) entered the study in Class 2a or 2b, with 56% improving and 24% worsening by study end. Among those in Class 1, 58% showed disease progression, highlighting pfCD’s refractory nature. Only 23% of the population achieved fistula healing. Subanalysis of the 16 patients starting in Class 2a (eligible for fistula closure) showed significant fistula healing (n=6) in those with less complex luminal disease and shorter CD duration (1.5 vs 17 years; p=0.02) and a non-penetrating, non-stricturing (Montreal B1) phenotype (100% vs 40%; p=0.03).The study highlighted treatment challenges, with 12% of patients requiring defunctioning surgery, 77% of whom had proctectomy. Of these, 55% progressed to Class 4, emphasising the need for careful preoperative and postoperative management.Conclusion Our retrospective study demonstrates strong face validity of the TOpClass classification, supporting its clinical applicability. The findings and gaps will inform a prospective trial to confirm TOpClass’s utility and enhance our understanding of pfCD.",
  "authors": [
    {
      "affiliations": [
        "School of Clinical Medicine, University of New South Wales Faculty of Medicine, Sydney, New South Wales, Australia",
        "IBD Unit, St Mark’s Hospital, Harrow, UK"
      ],
      "name": "Sulak Anandabaskaran"
    },
    {
      "affiliations": [
        "Imperial College London Department of Metabolism Digestion and Reproduction, London, UK"
      ],
      "name": "Luke Hanna"
    },
    {
      "affiliations": [
        "Department of Surgery, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands"
      ],
      "name": "Marte Becker"
    },
    {
      "affiliations": [
        "Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands"
      ],
      "name": "Christianne Buskens"
    },
    {
      "affiliations": [
        "Inflammatory Bowel Disease Center, The University of Chicago Medicine, Chicago, Illinois, USA"
      ],
      "name": "Benjamin D McDonald"
    },
    {
      "affiliations": [
        "Inflammatory Bowel Disease Center, The University of Chicago Medicine, Chicago, Illinois, USA"
      ],
      "name": "David T Rubin"
    },
    {
      "affiliations": [
        "Division of Colon and Rectal Surgery, Humanitas Clinical and Research Center IRCCS, Milan, Italy",
        "Department of Biomedical Sciences, Humanitas University, Milan, Italy"
      ],
      "name": "Michele Carvello"
    },
    {
      "affiliations": [
        "Division of Colon and Rectal Surgery, Humanitas Clinical and Research Center IRCCS, Milan, Italy",
        "Department of Biomedical Sciences, Humanitas University, Milan, Italy"
      ],
      "name": "Antonino Spinelli"
    },
    {
      "affiliations": [
        "Department of Gastroenterology and Hepatology, Ghent University Hospital, Ghent, Belgium"
      ],
      "name": "Jeroen Geldof"
    },
    {
      "affiliations": [
        "Department of Gastroenterology and Hepatology, Ghent University Hospital, Ghent, Belgium"
      ],
      "name": "Danny De Looze"
    },
    {
      "affiliations": [
        "Gastroenterology, Liverpool Hospital, Liverpool, New South Wales, Australia"
      ],
      "name": "Patrick Chan"
    },
    {
      "affiliations": [
        "School of Clinical Medicine, University of New South Wales Faculty of Medicine, Sydney, New South Wales, Australia",
        "Gastroenterology, Liverpool Hospital, Liverpool, New South Wales, Australia"
      ],
      "name": "Susan J Connor"
    },
    {
      "affiliations": [
        "Department of Surgery, Aarhus University Hospital, Aarhus, Denmark"
      ],
      "name": "Lilli Lundby"
    },
    {
      "affiliations": [
        "Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark"
      ],
      "name": "Anders Dige"
    },
    {
      "affiliations": [
        "Abdominal Surgery, University Hospitals Leuven, Leuven, Belgium"
      ],
      "name": "Gabriele Bislenghi"
    },
    {
      "affiliations": [
        "Gastroenterology, University Hospitals Leuven, Leuven, Belgium"
      ],
      "name": "Severine Vermeire"
    },
    {
      "affiliations": [
        "IBD Unit, St Mark’s Hospital, Harrow, UK"
      ],
      "name": "Ailsa Hart"
    },
    {
      "affiliations": [
        "Department of Surgery, Imperial College London Department of Surgery and Cancer, London, UK",
        "Robin Phillip’s Fistula Research Unit, St Mark’s Hospital and Academic Institute, Harrow, UK"
      ],
      "name": "Phil Tozer"
    }
  ],
  "title": "Functional validation of the TOpClass classification system for perianal fistulising Crohn’s disease using real-world multicentre data: a 10-year retrospective observational study",
  "uid": "a4680735-3c0d-52a1-94af-0c03cbfc3693"
}