Relapse rates after withdrawal of thiopurines in patients with inflammatory bowel disease

Withdrawal of thiopurines after remission is associated with an increased risk of relapse in patients with inflammatory bowel disease (IBD). However, long-term data on thiopurine withdrawal is limited, especially from developing countries where the cost of long-term therapy poses a significant burden on patients.

Patients with IBD on thiopurine monotherapy for ≥ 4 months, who stopped thiopurines while in clinical remission and were not on any other immunomodulator or biologics at the time of withdrawal, were included in this retrospective analysis.

Among 1093 patients with IBD on thiopurine monotherapy, 461 patients stopped thiopurine due to various reasons. Among these, 218 (ulcerative colitis (UC) = 179; Crohn's disease (CD) = 39) patients were in clinical remission and were continued on mesalamine. Overall, 36.7% (n = 80) relapsed after a median duration of 20 months (IQR: 9-49). Relapse rate was higher in UC than CD (39.7% vs 23%, p = 0.055). Cumulative probabilities of relapse were 17%, 34%, and 44% at the end of 1, 3, and 5 years, respectively. The relapse rate at 5 years was significantly lower in patients who had stopped azathioprine after 4 years of therapy (31% vs 54%, p = 0.007). On multi-variate cox regression analysis, male sex [HR: 1.6(1.0-2.6), p = 0.02] and short duration of therapy with thiopurines [HR: 1.02 (1.01-1.02), p = 0.004] before withdrawal were associated with increased risk of relapse.

Approximately 50% patients with IBD in remission would relapse after 5 years of thiopurine withdrawal. Male sex and shorter treatment duration predict relapse. Treatment should be continued in patients who tolerate and maintain remission on long-term thiopurine.