Development of the Robarts Histopathology Index

Whilst endoscopic mucosal healing is accepted as the current treatment goal in ulcerative colitis (UC), this treatment target is not “curative.” Disease relapse nevertheless occurs in patients who meet this outcome despite ongoing therapy and is frequently associated with persistent histological disease, present in approximately one-quarter of patients with normal appearing mucosa. Histological assessment has the potential to become the gold standard measure of inflammatory bowel disease activity, and outcomes assessing microscopic inflammation are now included as key endpoints in clinical trials for UC and increasingly Crohn’s disease. We recognized the need for a validated histological index for use in drug development and developed the Robarts Histological Index (RHI). The RHI is a valid instrument that exhibits highly consistent inter-observer reliability, and which is responsive to change in disease activity. This freely available index is now a component of disease activity assessment for the majority of drug development programs and may be easily derived from the Geboes score. The RHI is also an integral component of the UC-100, a highly responsive instrument that we developed for use in early drug development for UC.