Stored Intestinal Biopsies in Inflammatory Bowel Disease Research: A Danish Nationwide Population-Based Register Study.

Background. Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), is a complex inflammatory condition affecting the intestinal tract. Currently, immune-modulating treatments are inadequate for 30-50% of patients and often cause significant side effects, highlighting the urgent need for a personalized medicine approach. Real-world data and archived gut biological material from clinical repositories could be a resource for identifying new drug candidates and biomarkers. This study assesses the extent of stored formalin-fixed, paraffin-embedded (FFPE) gut biopsies from patients with IBD that could be leveraged for research efforts. Methods. Data from the Danish National Patient Register and the Danish Pathology Register were used to construct a cohort of patients diagnosed with IBD between 1 January 2005, and 30 June 2013, and followed for five years. Results. Among 14,512 IBD patients, 13,936 (96%) had at least one biopsy visit within five years after their initial diagnosis (CD 94%, UC 97%), and 13,598 (94%) had their first biopsy visit as part of the diagnostic process. Biopsies were taken from the colon (82%) or multiple locations (46%). Patients with severe disease had more biopsy visits than those with non-severe disease (IBD 3.3 vs. 2.0 visits, CD 2.9 vs. 1.9 visits, UC 3.6 vs. 2.0 visits). Conclusions. Thus, the vast majority of patients with IBD have biopsies taken. These findings demonstrate the feasibility and applicability of combining real-world data and archived gut biopsies for research, highlighting it as a valuable but underutilized resource for identifying new drug candidates and biomarkers, with huge potential for enhancing personalized medicine within IBD for the benefit of patients and society.