The use of azathioprine or 6-mercaptopurine for maintaining remission in Crohn’s disease patients who are steroid dependent or resistant is unequivocally supported by evidence from randomised controlled clinical trials. The same, however, cannot be said for the use of immunomodulator therapy in ulcerative colitis (UC). Trials are scanty, small in size, conflicting in results, and clinical practice is dominated by support from low quality evidence from open series reports. In addition, outcome measures used in different trials vary considerably, and the tools used to assess clinical disease activity are numerous and diverse.

In the first randomised controlled trial, conducted way back in 1974 by Jewell and Truelove,¹ a two by three stratification was used. Inpatients or outpatients with active UC were stratified into first attack, short history (less than five years), and long history (more than five years). The acute episode was treated with corticosteroids, either 20 mg oral prednisolone plus steroid enemas for outpatients or 40 mg prednisolone 21-phosphate with rectal hydrocortisone for inpatients. Azathioprine was added immediately at a dose of 2.5 mg/kg. In the first 40 patients, the azathioprine dose was reduced after three months to 1.5–2.0 mg/kg whereas in the next 40 patients the dose was maintained at 2.5 mg/kg throughout the trial period of one year. It was not surprising that azathioprine was of no value in induction of remission as the end point was at one month after commencement of azathioprine. As maintenance therapy, azathioprine lacked value in patients being treated for the first attack of UC. Although there was a trend towards some benefit in patients with established UC who had relapsed, this was not statistically significant. As the …