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

<b>Background.</b> 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. <b>Methods</b>. 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. <b>Results</b>. 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). <b>Conclusions</b>. 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.