{
  "abstract": "Background Primary sclerosing cholangitis associated inflammatory bowel disease (PSC-IBD) exhibits atypical inflammatory patterns that do not align with the conventional classification of ulcerative colitis (UC), Crohn’s disease (CD), or IBD unclassified (IBDu). We aimed to describe endoscopic inflammatory patterns in a national PSC-IBD cohort.Methods Colonoscopy data from PSC-IBD patients managed at 6 UK centres were analysed until last follow-up or colectomy. Segmental inflammatory involvement was determined from available reports. Right-sided-only (caecum, ascending, transverse colon ± terminal ileal (TI)), left-sided-only (rectum, sigmoid, descending colon) and other combinations were compared across classifications. Evolution of distribution was also assessed.Results 433 PSC-IBD patients were included (UC 352, CD 69, IBDu 12), with a median of 4 colonoscopies (2-7) over 8 years (5-12). No active disease was seen in 154 patients (36%). Only 13% of CD patients demonstrated stricturing or penetrating disease; upper GI involvement was absent and one patient had perianal disease. TI involvement differed by diagnosis (UC 3%, CD 15%, IBDu 17%; p<0.001). Caecal involvement was common across all diagnostic groups (UC 54%, CD 55%, IBDu 83%; p=0.141), as was rectal involvement (UC 46%, CD 38%, IBDu 42%; p=0.498). Rectal sparing was rare (≤4% in each; p=0.588).Right-sided-only disease occurred in 10% of UC, 17% of CD and 25% of IBDu patients (p=0.183), accounting for 9% of all procedures. Left-sided-only inflammation was uncommon (UC 7%, CD 1%, IBDu 0%; p=0.164). Overall, 37% of patients had inflammation in all colonic segments at some point (UC 36%, CD 28% and IBDu 25%; p=0.332). Non-contiguous colonic segmental involvement occurred less frequently in UC (5% vs CD 12%, IBDu 25%; p=0.014).At the first available colonoscopy that demonstrated inflammation, distribution was variable; right-sided-only 26%, left-sided-only 15%, TI-only 2%, with other combinations predominating (57%). 61 patients with available diagnostic procedures had mild disease severity (1; [1-1]) regardless of IBD type or segmental involvement, persisting throughout follow-up across the cohort. Both right- and left-sided disease showed comparable stability with 36% and 34% extending to other segments during follow-up. All patients with other segmental combinations remained within this group, and one patient with TI-only disease extended to the right colon.Conclusions In this large cohort, conventional IBD classifications inadequately describe PSC-IBD phenotype. Inflammatory distribution was heterogeneous and frequently right-weighted, with right-sided-only disease seen in all conventional groups. Inflammation was mild but persistent regardless of distribution. These findings support the need for a PSC-IBD-specific classification, incorporating segmental distribution and emphasise the importance of full colonoscopy for disease assessment.",
  "authors": [
    {
      "affiliations": [
        "King’s College Hospital, London, United Kingdom"
      ],
      "name": "Chandni Radia"
    },
    {
      "affiliations": [
        "Queen Elizabeth University Hospital, Glasgow, United Kingdom"
      ],
      "name": "Ross J Porter"
    },
    {
      "affiliations": [
        "Queen Elizabeth University Hospital, Glasgow, United Kingdom"
      ],
      "name": "Eleanor Peggie"
    },
    {
      "affiliations": [
        "Queen Elizabeth University Hospital, Glasgow, United Kingdom"
      ],
      "name": "Brian M Ou Yong"
    },
    {
      "affiliations": [
        "St George’s Hospital, London, United Kingdom"
      ],
      "name": "Michael Colwill"
    },
    {
      "affiliations": [
        "King’s College Hospital, London, United Kingdom"
      ],
      "name": "Chirag Patel"
    },
    {
      "affiliations": [
        "University College London Hospital, London, United Kingdom"
      ],
      "name": "Jie Han Yeo"
    },
    {
      "affiliations": [
        "University College London Hospital, London, United Kingdom"
      ],
      "name": "Paul Harrow"
    },
    {
      "affiliations": [
        "St George’s Hospital, London, United Kingdom"
      ],
      "name": "Kamal V Patel"
    },
    {
      "affiliations": [
        "Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom"
      ],
      "name": "Mark Samaan"
    },
    {
      "affiliations": [
        "Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom"
      ],
      "name": "Joel Mawdsley"
    },
    {
      "affiliations": [
        "Queen Elizabeth University Hospital, Glasgow, United Kingdom"
      ],
      "name": "Michael P Johnston"
    },
    {
      "affiliations": [
        "Queen Elizabeth University Hospital, Glasgow, United Kingdom"
      ],
      "name": "John Paul Seenan"
    },
    {
      "affiliations": [
        "John Radcliffe Hospital, Oxford, United Kingdom"
      ],
      "name": "Hannah Gordon"
    },
    {
      "affiliations": [
        "John Radcliffe Hospital, Oxford, United Kingdom"
      ],
      "name": "Emma Culver"
    },
    {
      "affiliations": [
        "King’s College Hospital, London, United Kingdom"
      ],
      "name": "Polychronis Pavlidis"
    },
    {
      "affiliations": [
        "King’s College Hospital, London, United Kingdom"
      ],
      "name": "Alexandra J Kent"
    }
  ],
  "title": "P184 Limitations of conventional IBD classification in PSC-IBD: a TAILOR-IBD study",
  "uid": "426de620-aefc-54b3-9a75-ed6de7e96d39"
}