Effective maintenance of inflammatory bowel disease remission by azathioprine does not require concurrent 5-aminosalicylate therapy.

OBJECTIVES: To assess the effect of 5-aminosalicylate treatment in conjunction with azathioprine on remission maintenance in inflammatory bowel disease patients.
METHOD: This retrospective study was based on a total of 186 inflammatory bowel disease patients (104 with Crohn's disease; 82 with ulcerative colitis), who were stable on azathioprine for a minimum of 6 months. The median duration of follow-up was 4.3 years (range 0.6-15.5 years). Relapse rates per year of follow-up were compared in an azathioprine + 5-aminosalicylate group (n = 103) and an azathioprine alone group (n = 83); survival curves for cumulative remission rates were compared by log-rank test. Discontinuation of azathioprine in both groups was also recorded, as was the incidence of malignancy.
RESULTS: In ulcerative colitis patients (n = 82), mean relapse rates for the azathioprine + 5-aminosalicylate group were 0.21/year compared with 0.19/year for the azathioprine alone group (P = not significant). In Crohn's disease patients (n = 104), mean relapse rates for the azathioprine + 5-aminosalicylate group were 0.27/year compared with 0.3/year for the azathioprine alone group (P = not significant). The cumulative remission percentage (determined from time to first relapse) was used in Kaplan-Meier survival analysis and showed no difference between the azathioprine + 5-aminosalicylate group and the azathioprine alone group by log-rank analysis, for ulcerative colitis and Crohn's disease as well as for all inflammatory bowel disease patients. Concurrent use of 5-aminosalicylates was no more frequent in patients who discontinued azathioprine due to adverse events. The only malignancy recorded was Waldenström's macroglobulinaemia after 7 years of azathioprine therapy.
CONCLUSION: Concurrent use of 5-aminosalicylate drugs did not reduce the relapse rates of inflammatory bowel disease patients who were established on azathioprine therapy. The use of 5-aminosalicylate drugs did not lead to any increase in discontinuation of azathioprine due to adverse events.