Outcomes and Reclassification Patterns in Inflammatory Bowel Disease Unclassified: A Multicenter Study Matched With Ulcerative Colitis From Spanish ENEIDA Registry

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. Methods 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. Results 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. Conclusions Therapeutic management of IBDU and UC patients tended to be similar. Two‐thirds of patients remained classified as IBDU.

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Journal
Journal of Gastroenterology and Hepatology
Published
2026-09-21
DOI
https://doi.org/10.1111/jgh.70745
Primary Topic
Inflammatory Bowel Disease
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article
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article

Outcomes and Reclassification Patterns in Inflammatory Bowel Disease Unclassified: A Multicenter Study Matched With Ulcerative Colitis From Spanish ENEIDA Registry

Jésus Barrio, Javier P. Gisbert, María José Casanova, F. Murciano et al.
Journal of Gastroenterology and Hepatology
Inflammatory Bowel Disease
article

Outcomes and Reclassification Patterns in Inflammatory Bowel Disease Unclassified: A Multicenter Study Matched With Ulcerative Colitis From Spanish ENEIDA Registry

Jésus Barrio, Javier P. Gisbert, María José Casanova, F. Murciano, M González-Vivó, Miquel Urpí, Marisa Iborra, Berta Caballol, Francisco Rodríguez‐Moranta, Lucía Márquez, Pablo Vega, Manuel Barreiro‐de Acosta, Eugeni Domènech, Marta Piqueras, Isabel Pérez‐Martínez, Laura Ramos, Yamile Zabana, Luís Bujanda, Rufo Lorente Poyatos, O. Belén‐Galipienso, V. Pedrera Roman, C. Tardillo Marin, B. Castro Senosiain
article en

Abstract

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. Methods 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. Results 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. Conclusions Therapeutic management of IBDU and UC patients tended to be similar. Two‐thirds of patients remained classified as IBDU.

Journal of Gastroenterology and Hepatology
Universitat Autònoma de Barcelona (ES), Hospital Universitario de Canarias (ES), Bellvitge University Hospital (ES), Hospital Universitari i Politècnic La Fe (ES), Hospital Universitario Nuestra Señora de Candelaria (ES), Hospital de Viladecans (ES), Consorci Sanitari de Terrassa (ES), Instituto de Investigación Marqués de Valdecilla (ES), Hospital General Universitario de Ciudad Real (ES), Mútua Terrassa (ES), Hospital Universitario de La Princesa (ES), Hospital Del Mar (ES), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (ES), Hospital General Universitario de Alicante Doctor Balmis (ES), Complexo Hospitalario Universitario A Coruña (ES), Instituto de Investigación Sanitaria de Santiago (ES), Hospital General San Jorge (ES), Hospital Universitario Río Hortega (ES), Complejo Hospitalario de Ourense (ES), Instituto de Investigación Sanitaria La Fe (ES), Instituto de Investigación Sanitaria del Principado de Asturias (ES), Universidad Autónoma de Madrid (ES)
Good health and well-being
Openalex Percentile: Top 11%
Inflammatory Bowel Disease
DOIOpen Access PDFOpenAlex
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