Thiopurines are superior to mesalamine for preventing postoperative recurrence in patients with Crohn's disease and two or more risk factors.

Objective: To confirm the hypothesis that thiopurines are better than mesalamine for preventing postoperative recurrence of Crohn's disease (CD) in patients with more than two risk factors.

Methods: In total 87 consecutive CD patients who underwent curative ileocolonic resection and ileocolic anastomosis were retrospectively recruited, including 43 prescribed with thiopurines and 44 with mesalamine after surgery. Four risk factors were predefined for subgroup analyses: smoking, penetrating disease, perianal disease and previous resection. End-points included clinical (Crohn's disease activity index >200) and endoscopic recurrence (Rutgeerts score ≥i2) within 52 weeks.

Results: There were no significant differences in clinical (37.2% vs 54.5%, P = 0.105) and endoscopic recurrence (55.8% vs 75.0%, P = 0.060) between the thiopurines and mesalamine groups by week 52. In the subgroup analysis of patients with two or more risk factors, clinical (35.7% vs 81.8%, P = 0.042) and endoscopic recurrence (64.3% vs 100%, P= 0.046) were less frequent in the thiopurine group than the mesalamine group. With one additional risk factor, the risk of endoscopic recurrence in the thiopurines group increased by 2.201-fold (95% confidence interval [CI] 1.178-4.115), adjusted for treatment intervention. While the risk of clinical and endoscopic recurrence in patients treated with mesalamine increased by 3.383-fold and 5.884-fold (95% CI 1.260-9.081 and 1.598-21.662). Three patients treated with thiopurines withdrew for adverse events.

Conclusions: Thiopurines may be superior to mesalamine for preventing postoperative recurrence of CD in patients with two or more risk factors. Caution is needed in light of the adverse events caused by thiopurines.