A prospective randomized observer-blind 2-year trial of azathioprine monotherapy versus azathioprine and olsalazine for the maintenance of remission of steroid-dependent ulcerative colitis

Am J Gastroenterol. 2004 Jun;99(6):1122-8. doi: 10.1111/j.1572-0241.2004.11481.x.


Objective: The aim of this prospective study was to assess whether the coadministration of azathioprine (AZA) and olsalazine is superior to AZA monotherapy in maintaining remission of steroid-dependent ulcerative colitis (UC).

Methods: Patients with steroid-dependent UC in remission were randomized to receive AZA alone (2.2 mg/kg) or in combination with olsalazine (0.5 g tid). Remission was defined as steroid withdrawal, an Ulcerative Colitis Clinical Activity Index (UCCAI) score of <2, an Ulcerative Colitis Disease Activity Index (UCDAI) score of 0, and a negative colonoscopy and histology. Patients were followed in the outpatient clinic every month for 2 yr. The study protocol included 1) monthly clinical examination, assessment of UCCAI, hematological and biochemical tests, and compliance with treatment; 2) a sigmoidoscopy and completion of inflammatory bowel disease quality-of-life questionnaire (IBD-Q) and UCDAI every 3 months; and 3) total colonoscopy with biopsies at the end of the first and second year of the trial.

Results: Seventy patients were randomized to receive AZA alone (n = 34) or with olsalazine (n = 36). Three patients in each group developed side effects or could not comply with treatment and were withdrawn from the study. Three patients receiving AZA relapsed after the first year of the study and three after the second year of the study (19%). In the combination therapy group four patients relapsed after the first year of study and two after the second year of the study (18%). Relapse rates were not significant whether analyzed by intention-to-treat or per protocol. There were no significant differences between groups in time to relapse or discontinuation of treatment, UCCAI, UCDAI, or IBD-Q scores. However, the number of adverse events and the cost of treatment were significantly higher, whereas compliance with treatment was poorer in the combination therapy.

Conclusion: Patients with steroid-dependent UC successfully maintained in remission on AZA are not in need of 5-aminosalicylic acid compounds.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aminosalicylic Acids / administration & dosage*
  • Analysis of Variance
  • Azathioprine / administration & dosage*
  • Colitis, Ulcerative / diagnosis*
  • Colitis, Ulcerative / drug therapy*
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Drug Therapy, Combination
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Remission Induction*
  • Risk Assessment
  • Severity of Illness Index
  • Single-Blind Method
  • Statistics, Nonparametric
  • Steroids / therapeutic use
  • Treatment Outcome


  • Aminosalicylic Acids
  • Steroids
  • Azathioprine
  • olsalazine