Azathioprine Based on Endoscopy After Clinical Remission in Moderate to Severe Ulcerative Colitis

The aim of this study is to determine whether azathioprine is effective for mucosal healing in UC patients who achieved clinical remission by the first course of corticosteroids but not mucosal healing in endoscopy.

The sample size was calculated based on the previous study showing the difference of mucosal healing rate between azathioprine (58%) and 5-aminosalicylate (21%). With a two-tailed test of α = 0.05 and 1 - ß = 0.8, 52 patients were required.

The placebo drug which is identical to azathioprine will be provided by Celltrion drug company.

Differences in the categorical variables between the groups are examined with χ2 or the Fisher exact test. For comparisons of continuous variables, a Student t test is used.

Inclusion Criteria:

• Ulcerative colitis patients with moderate to severe activity who achieved a clinical remission by the first course of corticosteroids
• Newly diagnosed or without steroid use during last 1 year
• Endoscopic Mayo subscore >0

Exclusion Criteria:

• Patients with azathioprine or biologics therapy