Methods: A multicentre randomized controlled trial was conducted to evaluate the efficacy of oral mesalazine (5-aminosalicylic acid) for the prevention of post-operative recurrence in 110 patients operated on for Crohn's disease by first intestinal resection. Patients were randomly allocated to receive 2.4 g/day of mesalazine, or no treatment at all. The protocol included colonoscopy with ileoscopy at 6 months and yearly thereafter. Recurrence was denned on the basis of endoscopic criteria and classified as mild or severe.
Results: The demographic and pre-trial characteristics were very similar in the two groups of patients. The cumulative proportion of recurrence at 6, 12 and 24 months was significantly lower in the mesalazine group than in untreated group (P= 0.002). At 24 months the cumulative proportions of endoscopic recurrence were 0.52 + 0.12 (± S.E.M.) and 0.85 (±0.07), respectively. At the same time the cumulative proportions of symptomatic recurrence were 0.18 + 0.09 and 0.41 + 0.09 (P= 0.006). The cumulative proportions of the severe recurrence was also significantly lower in the mesalazine group (0.17±0.09 vs. 0.38±0.09; P= 0.021). Conclusions: The preliminary results of this study show that administration of oral mesalazine soon after surgery is effective in preventing post-operative endoscopic recurrence in Crohn's disease over a 2-year period. It is estimated that this treatment prevents 39% of all recurrences and 55% of the severe recurrences.