{ "abstract": "Background and Aim: Around 10% of patients with inflammatory bowel disease do not fulfill the diagnostic criteria for Crohn's disease (CD) or ulcerative colitis (UC). These cases are labelled as inflammatory bowel disease unclassified (IBDU). The aim of the study was to compare therapeutic requirements in patients with IBDU and UC and to identify predictive factors of reclassification.\n\nMethods: This was a multicenter retrospective cohort study based on the ENEIDA registry. Patients diagnosed with IBDU or indeterminate colitis between January 2010 and December 2016 were included. All cases were matched by sex, age at diagnosis, and disease extent with at least two UC patients from the same hospital. The Kaplan–Meier method was performed to assess diagnostic changes during follow‐up. Fine–Gray competing‐risks regression analysis identified predictive factors of reclassification.\n\nResults: Two hundred and nine IBDU patients and 465 UC patients were included. After a median follow‐up of 90 months, no significant differences were observed in the use of immunomodulator (37.3% vs. 37%, p = 0.934) and advanced therapies (29.2% vs. 23.9%, p = 0.143) between IBDU and UC. No statistical differences were found in the surgical rates (5.7% vs. 4.7%, p = 0.579). Overall, 59 IBDU patients (28.2%) were reclassified (30 UC and 29 CD). Baseline extensive colitis was associated with a lower probability of subsequent reclassification to UC (SHR: 0.33; 95% CI: 0.12–0.91). No independent predictive factors for reclassification to CD were identified.\n\nConclusions: Therapeutic management of IBDU and UC patients tended to be similar. Two‐thirds of patients remained classified as IBDU.", "abstract_shown": true, "affiliations": [ "Hospital de Viladecans Viladecans Spain", "Hospital del Mar Medical Research Institute (IMIM) Hospital del Mar Barcelona Spain", "Instituto de Investigación IDIVAL Hospital Universitario Marqués de Valdecilla Santander Spain", "Instituto de Investigación Biosanitaria del Principado de Asturias (ISPA) Hospital Universitario Central de Asturias Oviedo Spain", "Gerencia Regional de Salud de Castilla y León (SACYL) Hospital Universitario Río Hortega Valladolid Spain", "Complexo Hospitalario Universitario de Ourense Ourense Spain", "Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) Hospital Clínic de Barcelona, Centro de Investigación Biomédica en Red Enfermedades Hepáticas y Digestivas (CIBERehd) Barcelona Spain", "Hospital Universitario San Jorge Huesca Spain", "Consorci Sanitari de Terrassa Terrassa Spain", "Hospital Universitari de Bellvitge Hospitalet de Llobregat L'Hospitalet de Llobregat Spain", "Inflammatory Bowel Disease Research Group, Health Research Institute La Fe (IIS La Fe). IBD Unit, Gastroenterology Department La Fe University and Polytechnic Hospital Valencia Spain", "Instituto de Investigación Sanitaria Princesa (IIS‐Princesa) Hospital Universitario de La Princesa, Universidad Autónoma de Madrid (UAM), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD) Madrid Spain", "Hospital Universitario Nuestra Señora de Candelaria Santa Cruz de Tenerife Spain", "Hospital Universitario de Canarias Santa Cruz de Tenerife Spain", "Hospital General Universitario de Ciudad Real Ciudad Real Spain", "Fundación Galega de Investigación Sanitaria (IDIS) Hospital Clínico Universitario de Santiago Santiago de Compostela Spain", "ISABIAL Hospital General Universitario Dr Balmis de Alicante Alicante Spain", "Instituto Biodonostia Universidad del País Vasco (UPV/EHU), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) San Sebastián Spain", "Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Hospital Universitari Mutua Terrassa Terrassa Spain", "Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Hospital Universitari Germans Trias i Pujol Badalona Spain", "Universitat Autònoma de Barcelona Barcelona Spain" ], "article_type": "research article", "arxiv": null, "author_total": 24, "authors": [ { "affs": [ 0, 1 ], "name": "M. González‐Vivó", "orcid": "0000-0001-5857-3766" }, { "affs": [ 2 ], "name": "B. Castro Senosiain" }, { "affs": [ 3 ], "name": "I. Pérez‐Martínez", "orcid": "0000-0002-2535-1929" }, { "affs": [ 4 ], "name": "J. Barrio", "orcid": "0000-0001-7087-3921" }, { "affs": [ 5 ], "name": "P. Vega Villaamil", "orcid": "0000-0001-7545-6297" }, { "affs": [ 6 ], "name": "B. Caballol Oliva", "orcid": "0000-0002-7921-6730" }, { "affs": [ 7 ], "name": "V. Pedrera Roman" }, { "affs": [ 8 ], "name": "M. Piqueras Cano", "orcid": "0000-0002-3874-2638" }, { "affs": [ 9 ], "name": "F. Rodríguez Moranta", "orcid": "0000-0003-4025-5510" }, { "affs": [ 10 ], "name": "M. Iborra", "orcid": "0000-0001-7360-7581" }, { "affs": [ 11 ], "name": "M. J. Casanova", "orcid": "0000-0001-8233-9638" }, { "affs": [ 11 ], "name": "J. P. Gisbert", "orcid": "0000-0003-2090-3445" }, { "affs": [ 12 ], "name": "C. Tardillo Marin", "orcid": "0000-0002-0835-2831" }, { "affs": [ 13 ], "name": "L. Ramos", "orcid": "0000-0001-7015-1742" }, { "affs": [ 1 ], "name": "M. Urpi‐Ferreruela", "orcid": "0000-0001-7301-1884" }, { "affs": [ 14 ], "name": "R. H. Lorente Poyatos", "orcid": "0000-0003-0709-2932" }, { "affs": [ 15 ], "name": "M. Barreiro‐de Acosta", "orcid": "0000-0001-5915-1477" }, { "affs": [ 16 ], "name": "O. Belen Galipienso", "orcid": "0000-0001-9105-831X" }, { "affs": [ 17 ], "name": "L. Bujanda", "orcid": "0000-0002-4353-9968" }, { "affs": [ 18 ], "name": "Y. Zabana", "orcid": "0000-0003-4023-8868" }, { "affs": [ 1 ], "name": "F. Murciano", "orcid": "0000-0002-0239-8193" }, { "affs": [ 19, 20 ], "name": "E. Domènech", "orcid": "0000-0002-2315-7196" }, { "affs": [ 1 ], "name": "L. Márquez‐Mosquera", "orcid": "0000-0002-3182-9570" }, { "name": "ENEIDA registry of GETECCU" } ], "bibtex": "https://research.draconitic.com/paper/ap6rc5nt4dkec.bib", "cited_by": 0, "doi": "10.1111/jgh.70745", "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13731003/", "id": "ap6rc5nt4dkec", "issns": [ "0815-9319", "1440-1746" ], "landing_url": "https://doi.org/10.1111/jgh.70745", "language": "en", "licence": "CC-BY-NC-ND-4.0", "licence_label": "CC BY-NC-ND 4.0", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/", "metadata_licence": null, "native_subjects": [ [ "heading", "Original Article ‐ Gastroenterology (Clinical)" ], [ "openalex", "2715|Inflammatory Bowel Disease" ] ], "openalex": "W7213972270", "pdf_url": "https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/jgh.70745", "pmcid": "PMC13731003", "pmid": "42768837", "published": "2026-09-21", "publisher": null, "ris": "https://research.draconitic.com/paper/ap6rc5nt4dkec.ris", "sources": [ { "first_seen": "2026-11-08T12:21:17Z", "native_id": "PMC13731003", "source": "pmc", "url": "https://doi.org/10.1111/jgh.70745" } ], "subjects": [ { "field": "medicine", "origin": "openalex:2715|Inflammatory Bowel Disease", "subfield": "general" } ], "title": "Outcomes and Reclassification Patterns in Inflammatory Bowel Disease Unclassified: A Multicenter Study Matched With Ulcerative Colitis From Spanish ENEIDA Registry", "title_text": "Outcomes and Reclassification Patterns in Inflammatory Bowel Disease Unclassified: A Multicenter Study Matched With Ulcerative Colitis From Spanish ENEIDA Registry", "type": "peer-reviewed", "updated_at": "2026-11-08T12:21:17Z", "url": "https://research.draconitic.com/paper/ap6rc5nt4dkec", "venue": "Journal of Gastroenterology and Hepatology", "versions": [] }