Azathioprine is superior to budesonide in achieving and maintaining mucosal healing and histologic remission in steroid-dependent Crohn's disease.

Background: The effects of azathioprine (AZA) and budesonide (BUD) on mucosal healing and histologic remission of Crohn's disease (CD) are insufficiently studied. In this prospective study we evaluated the comparative effects of AZA and BUD on endoscopic and histologic activity in patients with steroid-dependent Crohn's ileocolitis or proximal colitis who had achieved clinical remission on conventional steroids.

Methods: Patients were randomized to AZA (2.0-2.5 mg/kg a day) or BUD (6-9 mg a day) for 1 year. The study protocol included clinical examination, laboratory tests, calculation of the Crohn's Disease Activity Index (CDAI), completion of the Inflammatory Bowel Disease Questionnaire (IBDQ), at baseline and then every 2 months for 1 year. Ileocolonoscopy with regional biopsies was performed at baseline and then at the end of the study to assess mucosal healing and the histologic activity of CD.

Results: Thirty-eight patients were randomized to AZA and 39 to BUD. At the end of the study 32 and 25 patients in the AZA and BUD groups, respectively, were in clinical remission (P = 0.07). The Crohn's Disease Endoscopic Index of Severity (CDEIS) score fell significantly only in the AZA group (P < 0.0001). Complete or near complete healing was achieved in 83% of AZA-treated patients compared with only 24% of BUD-treated patients (P < 0.0001). Histologic activity as assessed by an average histology score (AHS) fell significantly only in the AZA group (P < 0.001 versus baseline) and was significantly lower than in the BUD group at the end of the study (P < 0.001). Eight patients in the AZA group were withdrawn for adverse events (n = 6) or relapse of disease compared with 14 patients in the BUD group who were withdrawn for relapse of disease.

Conclusions: In patients with steroid-dependent inflammatory Crohn's ileocolitis or proximal colitis who achieve clinical remission with conventional steroids, a 1-year treatment with AZA was superior to BUD in achieving and maintaining mucosal healing and histologic remission.