The impact of thiopurines on the risk of surgical recurrence in patients with Crohn's disease after first intestinal surgery.

Objectives: Smoking and a lack of immunosuppressive (IS) therapy are considered risk factors for intestinal surgery in Crohn's disease (CD). Good evidence for the latter is lacking. The objective of this study was to evaluate the impact of thiopurine treatment on surgical recurrence in patients after first intestinal resection for CD and its possible interaction with smoking.

Methods: Data on 326 patients after first intestinal resection were retrieved retrospectively, and subjects were grouped according to their postoperative exposure to thiopurines. Treatment with either azathioprine (AZA) or 6-mercaptopurine (6-MP) was recorded on 161 patients (49%). Smoking status was assessed by directly contacting the patients.

Results: Surgical recurrence occurred in 151/326 (46.3%) patients after a median time of 71 (range 3-265) months. Cox regression revealed a significant reduction of re-operation rate in patients treated with AZA/6-MP for > or = 36 months as compared with patients treated for 3-35 months, for less than 3 months, and to those without postoperative treatment with AZA/6-MP (P=0.004). Cox regression analysis revealed treatment with thiopurines for > or = 36 months (hazard ratio (HR) 0.41; 95% confidence interval (CI) 0.23-0.76, P=0.004) and smoking (HR 1.6; 95% CI 1.14-2.4, P=0.008) as independent predictors for surgical recurrence. Furthermore, longer duration of disease tended to be protective (HR 0.99; 95% CI 0.99-1.0, P=0.067).

Conclusions: Long-term maintenance treatment with AZA/6-MP reduces the risk of surgical recurrence in patients with CD. We also identified smoking as a risk factor for surgical recurrence.