Correlation between endoscopic severity and the clinical activity index in ulcerative colitis

OBJECTIVE: The aim of this study was to examine the relationship between a new activity index and the endoscopic severity assessed by sigmoidoscopy in patients with ulcerative colitis. METHODS: We evaluated the sigmoidoscopic severity and Activity Index (AI) in 37 patients with distal colitis, 23 with left-sided colitis, and 36 with total colitis, in which the severity was divided into three categories: grade 1 = mildly active, grade 2 = moderately active, and grade 3 = severely active. We examined the relationship between the AI or clinical parameters and the endoscopic severity in all 96 cases. RESULTS: The AI was found to be significantly correlated with the degree of sigmoidoscopic activity in all cases, as well as in those with distal colitis, left-sided colitis, or total colitis. When patients with both grade 1 sigmoidoscopic activity and AI values of less than 150 were regarded to have mild colitis and patients with either grade 2 or grade 3 sigmoidoscopic activity and AI values of more than 150 were regarded to have moderate or severe colitis, 10 of 37 (27%) in the distal colitis, one of 23 (4.3%) in the left-sided colitis, and four of 36 (11.1%) in the total colitis groups were thus misclassified regarding the distinction between mild colitis and moderate or severe colitis. Three of four patients with severity of grade 1, indicating AI values of more than 150, had total colitis, whereas the remaining one had left-sided colitis. On the other hand, 10 of 11 patients with severity of grades 2 or 3 with AI values of less than 150 had distal colonic involvement. When the endoscopic activity was equivalent, the highest mean AI values occurred in total colitis whereas the lowest mean AI values were found in distal colitis. CONCLUSIONS: The AI well reflects the sigmoidoscopic activity. High AI values with a low sigmoidoscopic severity are thus considered to reflect extensive involvement, whereas a high sigmoidoscopic severity with low AI values is thought to indicate the involvement of the distal colon.