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* = Presenting author

P616 Different profile of efficacy of thiopurines in Ulcerative Colitis and Crohn's Disease

A. Testa*1, A. Rispo1, M. Rea1, G.D. De Palma2, M. Diaferia1, D. Musto1, F. Sasso1, N. Caporaso1, F. Castiglione1

1AOU Policlinico Federico II of Naples, Gastroenterology, Naples, Italy, 2AOU Policlinico Federico II of Naples, Surgery and Advanced Technologies, Naples, Italy

Background

Azathioprine (AZT) and 6-mercaptopurine (6-MP) are effective drugs in treating ulcerative colitis (UC) and Crohn's disease (CD) as they can induce/maintain clinical remission (CR) and mucosal healing (MH) in steroid-dependent patients. Nevertheless, studies directly investigating a possible different profile of efficacy in UC in comparison with CD are scarce. Aim: to explore the rate of CR and MH in UC patients treated by thiopurines compared to that of subjects with CD.

Methods

We performed an observational longitudinal study evaluating steroid-free CR and MH in all UC and CD patients who would complete 2 years of maintenance treatment with thiopurines. Patients characteristics were classified according to the ECCO guidelines. CR and MH were assessed before starting treatment and 2 years later by Mayo score for UC (CR= Mayo score <2; MH= Mayo sub-score <1); CR and MH were assessed at same time-points by Crohn's disease activity index (CR=CDAI< 150) and Simplified Endoscopic Score for Crohn's Disease (MH=SES-CD <2) for CD. Statistical analysis was performed using chi-square, Mann-Whitney U test and odd ratio( OR) where appropriate. To test the concordance between CR and MH in UC and CD, the Cohen's k measure was applied. Regarding the differences in outcomes for CR and MH we estimated that a total sample size of 120 patients would allow detection of a 20% difference between the 2 groups.

Results

The study included 70 patients with UC (AZT/6-MP=60/10; M/F=37/33; mean age=39 years; E1=0, E2=24, E3=46;mean baseline Mayo score=8.5) and 70 subjects with CD (AZT/6-MP=62/8; M/F= 39/31; mean age=33 years; L1=34, L2=26, L3=10;B1=54, B2=10, B3=6; mean baseline CDAI=290) treated with thiopurines for 2 years. At the end of the study, steroid-free CR was recorded in 43 patients with UC and 37 with CD (61% vs 53%; p=0.3). MH was obtained in 38 patients with UC and 17 with CD (54% vs 25%; p<0.01; O.R.=4.5). The concordance between CR and MH was higher in UC patients than in subjects with CD (k=0.71in UC; k=0.41 in CD).

Conclusion

Thiopurines are equally effective in maintaining steroid-free clinical remission in both UC and CD even if with a better profile of efficacy in UC in terms of mucosal healing. Our data confirm the higher concordance between clinical and endoscopic findings in UC compared to that observed in CD patients.