The disease activity of ulcerative colitis and Crohn's disease.

The disease activity in ulcerative colitis and Crohn's disease was studied. Parameters found to reflect the disease activity were given scores from 1 to 4. The score obtained by a patient compared with the maximum scores gives the percentage disease activity. The regressions between the percentage disease activity and the ESR in ulcerative colitis and Crohn's disease were r=0.68 (p less than 0.001) and r=0.48 (p less than 0.001), respectively. The different activity parameters have different time response curves explaining the occasional slight correlation. The percentage disease activity represents the mean activity of the different parameters at a given time. It is proposed to define slight, moderate, and severe ulcerative colitis or Crohn's disease as percentage disease activity of less than 30, 30-70 and greater than 70 per cent, respectively.