Definition of mild to moderate ulcerative colitis in clinical trials: A systematic literature review.

We performed a systematic review to investigate the definition of mild to moderate active ulcerative colitis (UC), and to describe predictors of good response to treatment in clinical trials assessing 5-ASA and/or budesonide. Thirty-nine randomized controlled trials were included. The UC Disease Activity Index (UCDAI) was the most frequent score used for defining mild to moderate active UC (16 studies, 41%), followed by Clinical Activity Index in 11 studies (28.2%). Four different cut-offs were used to define mild to moderate active UC using the UCDAI. The most frequently reported predictors of good response to treatment was a mild and moderate disease activity. There is heterogeneity in the definition of mild to moderate active UC in randomized clinical trials. A standardized definition of mild to moderate active UC used for inclusion of patients in clinical trials is needed.