Azathioprine Is Useful for Maintaining Long-term Remission Induced by Tacrolimus for the Treatment of Ulcerative Colitis: An Inverse Probability of a Treatment Weighing Analysis

OBJECTIVE: The need for and efficacy of immunomodulators for maintaining remission after tacrolimus therapy have not been sufficiently defined. This study evaluated the efficacy of immunomodulators for maintaining remission in patients with ulcerative colitis after tacrolimus therapy. METHODS: Patients with active ulcerative colitis who started oral tacrolimus between January 2009 and September 2017 and were responsive were retrospectively evaluated. Long-term outcomes were compared using Cox proportional hazard regression with inverse probability of treatment weighting. RESULTS: Among the 63 patients in the study, 45 received immunomodulators. During the follow-up, 30 patients (47.6%) experienced a relapse. The relapse-free survival rate was significantly worse in the group that did not receive immunomodulators than in those that did (p=0.01, log-rank test); the 2-year relapse-free rates were 22.5% and 63.6% in the non-immunomodulator and immunomodulator groups, respectively. A multivariate analysis showed immunomodulator treatment to be an independent protective factor for clinical relapse (adjusted hazard ratio: 0.35, 95% confidence interval: 0.16-0.78, p=0.01). A Cox regression analysis using inverse probability of treatment weighting also showed that immunomodulator maintenance therapy was correlated with a longer relapse-free survival (hazard ratio: 0.31, 95% confidence interval: 0.15-0.64, p<0.01), A similar response was also observed in non-steroid-dependent patients (hazard ratio: 0.36, 95% confidence interval: 0.14-0.99, p=0.047). No serious adverse events occurred due to tacrolimus or immunomodulator, and immunomodulator use did not increase the incidence of adverse events caused by tacrolimus. CONCLUSION: Our data suggest that the use of immunomodulators to maintain remission after tacrolimus therapy is beneficial for patients with ulcerative colitis.