Systematic Review and Meta - Analysis of the Frequency and Re-Classification Trends of Pediatric Inflammatory Bowel Disease - Unclassified

Abstract

Background: The term inflammatory bowel disease-unclassified (IBDU) is used when an individual has chronic colitis but cannot be sub-typed into ulcerative colitis (UC) or Crohn’s disease (CD) on the basis of the clinical, endoscopic, imaging and histopathological features. On follow-up a proportion of patients with IBDU are re-classified as CD or UC. There has been considerable variability in the frequency and reclassification rates of pediatric IBDU in published literature. Methods: PubMed and Scopus and were searched for publications related to Pediatric Inflammatory Bowel Disease (PIBD) published between Jan,2014 and July,2021. Two reviewers independently searched and selected studies reporting the frequency of IBDU and/or their re-classification. The pooled prevalence was expressed as proportion and 95%CI. Meta-analysis was performed using the inverse variance heterogeneity model. Results: A total of 2750 studies were identified through a systematic search of which 27 studies were included in this systematic review. The overall pooled frequency of IBDU (n=16064) was found to be 7.1% (95%CI 5.8-8.5%). There was no variation in IBDU frequency by geographical location. Seven studies (n=5880) were included in the IBDU re-classification analysis. Overall, 50% (95%CI 41-60%) children with IBDU were re-classified on follow-up. Amongst these 32.7% (95% 21-44%) were re-classified to UC and 17% (95%CI 12-22%) were re-classified to CD. Conclusion: IBDU comprises 7.1% of PIBD at initial diagnosis. Half of these children are re-classified into UC or CD on follow-up with a higher likelihood of re-classification to UC as compared to CD.