TOpCLASS Expert Consensus Classification of Perianal Fistulising Crohn's Disease: A Real-world Application in a Serial Fistula MRI Cohort.

The TOpCLASS classification highlights the dynamic nature of PFCD over time. However, our ability to predict transitions between classes remains limited and requires prospective assessment. Improvement in MRI index scores over time was associated with a transition to lower TOpCLASS classification.