DOP081 Long-term natural history of postoperative recurrence in patients on preventive treatment with azathioprine

Results: Overall, 8673 patient met our inclusion criteria of which 479 went on to have a total colectomy during follow up. 52% of patients were male and the median age of the cohort was 46 years. The overall 5 year colectomy rate over the whole period of follow up was 5.9% (95%CI: 5.4 6.5%). Colectomy was more common in males (62.2% vs 37.8%, p < 0.001). The 5 year colectomy rate was 4.2%, 5.1% and 6.9% for era 1, era 2 and era 3 respectively (p = 0.001 via Log-rank testing) (Figure 1). The 5 year probability of receiving a thiopurine was 10.9%, 19.3% and 27.9% for era 1, era 2 and era 3 respectively (p < 0.001, via Log-rank testing) (Figure 2). Furthermore, the proportion of early thiopurine users within the first year of diagnosis increased by era and was 4.6%, 9.6% and 13.4% (c2 p < 0.001).