Efficacy of azathioprine in mild or moderate relapse in Crohn's disease: clinical and endoscopic evaluation.

Aim:  The present study was aimed at evaluating the efficacy of azathioprine (AZA) in patients with active and relapsing Crohn's disease (CD) and the usefulness of endoscopy in this evaluation. Methods:  The 53 patients with active CD treated with AZA at our hospital were subjected to the following retrospective analysis: (i) evaluation of the clinical efficacy of AZA through comparison of the Crohn's disease activity index (CDAI); (ii) analysis of the relationship of the clinical efficacy to the difference in the mean corpuscular volume (MCV); (iii) evaluation of mucosal healing through analysis of the scores of the endoscopic findings in 16 patients; and (iv) analysis of the relapse rate. Results:  (i) Among the 53 patients, treatment was rated as having induced complete remission in 22.6%, as being effective in 41.5%, and as being ineffective in 13.3% of patients. The treatment was discontinued in 22.6% of patients. (ii) The post-treatment MCV was significantly increased after treatment. (iii) When the ulcer score estimated after treatment was compared with that before the start of treatment, a significant improvement of the score was noted. (iv) When the non-relapse rate after AZA therapy was calculated in the 41 patients followed up for 12 months, it was 84.8%. Conclusion:  AZA was shown to cause endoscopic mucosal healing as well as clinical efficacy. In the present study, it was inferred that the efficacy of AZA therapy in CD patients is manifested clinically first and that mucosal healing is an effect that occurs later.