My master's thesis focused on Inflammatory Bowel Disease Unclassified (IBDU), a rare entity within the broader spectrum of Inflammatory Bowel Disease (IBD), which also includes Crohn's disease and ulcerative colitis. The primary objective of this study was to characterize the IBDU population in Switzerland, specifically focusing on the evolution of disease location and the treatments received. To accomplish this, a retrospective analysis was conducted using data from the prospective cohort study known as "The Swiss Inflammatory Bowel Disease Cohort Study" from 2006 to the present. A total of 145 patients diagnosed with IBDU were enrolled. Data were collected at the time of inclusion and during annual follow-ups.
The key findings are as follows: the predominant disease location identified among our patients was pancolitis, both at diagnosis and during the last follow-up. Moreover, a significant proportion of patients had utilized biologic agents at least once. At the last follow- up, 106 patients remained classified as IBDU, while 13 had been reclassified as CD, and 26 as UC.
However, it is essential to acknowledge the limitations of this study, including variability in disease duration and retrospective data collection. Additionally, the study's sample size should be considered when generalizing these findings. Future analyses should consider data processing for patients with diagnostic changes and explore histological analyses to gain a deeper understanding of disease progression and severity.