Background
Studies assessing the efficacy of azathioprine in steroid-dependent patients with Crohn's disease are scarce. The aim of this study was to assess the long-term efficacy and safety of azathioprine, and factors associated with sustained response, in steroid-dependent patients with Crohn's disease.
Material and Method
In this prospective, observational study, adult steroid-dependent subjects with Crohn's disease receiving azathioprine therapy were assessed over a 10-year period. Azathioprine dosage was adjusted according to clinical response and occurrence of adverse events. Median treatment duration was 83 months. Steroid therapy was tapered according to protocol.
Results
A total of 106 subjects were included. The proportion of subjects remaining in sustained steroid-free remission at 12, 24, 36, 48, and 60 months was 0.61, 0.73, 0.72, 0.70, and 0.70, respectively. Thereafter, the rate of weaning from steroids decreased gradually, reaching a nadir of 0.41 at 108 months. Median time to complete steroid withdrawal was 6 months. Demographic, azathioprine dose, and disease-related data did not correlate with remission. By multivariate analysis, only decreased mean leukocyte count during follow-up was independently associated with steroid-free remission (P=.001). Subjects who achieved an annual mean leukocyte count <6,000/mm(3) were more likely to sustain steroid-free remission (P=.01). Serious adverse events in response to azathioprine were uncommon.
Conclusions
Azathioprine therapy offers a meaningful option in the management of steroid-dependent Crohn's disease for up to 10 years. A persistent decrease in leukocyte count may provide a surrogate marker of sustained steroid-free response.

Keywords: Prospective Studies, Longitudinal Studies, Follow-Up Studies, Crohn Disease - drug therapy, Azathioprine - therapeutic use, Adrenal Cortex Hormones - therapeutic use