Introduction Thiopurine therapy is effective in maintaining clinical remission in IBD. However, long-term therapy is associated with an increased risk of lymphoma; therefore in clinical practise it may be appropriate to withdraw thiopurines after prolonged remission. Nevertheless, many patients will experience disease relapse within 12 months of drug withdrawal.
The Aim of the present study was to retrospectively determine the relapse rate in ulcerative colitis (UC) and Crohn’s disease (CD) following azathioprine (AZA) or mercaptopurine (MP) withdrawal and to determine factors predictive of relapse.
Methods Patients were identified by electronic case note review of IBD patients in eight major centres around the United Kingdom. Major inclusion criteria were AZA and/or MP therapy for a minimum of 3 years, AZA/MP withdrawn due to sustained clinical remission no steroid therapy for 6 months prior to drug withdrawal, and minimum 12 months follow-up.
The primary outcome was disease relapse requiring AZA reinitiation, steroids or colectomy within 12 months of AZA/MP withdrawal, with secondary outcome assessed at 24 months. Clinical/laboratory predictors of relapse were sought.
Results Data was obtained on 97 patients with CD and 78 with UC. Median age at diagnosis was 26y (interquartile range [IQR] 20–38), and 49% were female. Median duration of thiopurine use was 73 months (IQR 54–104). Median duration of follow-up was 39 months (IQR 24–65 months).
CD was associated with a significantly higher risk of relapse than UC on Kaplan Meier analysis (Figure 1, p = 0.024). The moderate-severe relapse rate for 12 months was 27% for CD and 14% for UC. For 24 months, relapse rates were 41% for CD and 28% for UC. Elevated CRP was predictive of relapse at 12 months for CD (0 = 0.017), while elevated platelet count was predictive of relapse at 24 months for UC (0.021).
Retreatment with a thiopurine after relapse was successful in 34/39 (87%) for CD and 17/18 (94%) cases for UC.
Conclusion Relapse rates after withdrawal of a thiopurine are high, particularly for CD, and predicting this remains difficult. The findings regarding CRP and CD in this data highlight the importance of ensuring patients are in deep remission prior to drug withdrawal. Further studies should evaluate the role of faecal calprotectin in this.
Disclosure of Interest None Declared.
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