Thiopurines Have Longer Treatment Durability than Methotrexate in Adults and Children with Crohn's Disease: A Nationwide Analysis from the epi-IIRN Cohort

Background: Thiopurines and methotrexate have long been used to maintain remission in Crohn's disease [CD]. In this nationwide study, we aimed to compare the effectiveness and safety of these drugs in CD. Methods: We used data from the epi-IIRN cohort, including all patients with CD diagnosed in Israel. Outcomes were compared by propensity-score matching and included therapeutic failure, hospitalisations, surgeries, steroid dependency, and adverse events. Results: Of the 19264 patients diagnosed with CD since 2005, 3885 [20%] ever received thiopurines as monotherapy and 553 [2.9%] received methotrexate. Whereas the use of thiopurines declined from 22% in 2012-2015 to 12% in 2017-2020, the use of methotrexate remained stable. The probability of sustaining therapy at 1, 3, and 5 years was 64%, 51%, and 44% for thiopurines and 56%, 30%, and 23% for methotrexate, respectively [p <0.001]. Propensity-score matching, including 303 patients [202 with thiopurines, 101 with methotrexate], demonstrated a higher rate of 5-year durability for thiopurines [40%] than methotrexate [18%; p <0.001]. Time to steroid dependency [p = 0.9], hospitalisation [p = 0.8], and surgery [p = 0.1] were comparable between groups. These outcomes reflect also shorter median time to biologics with methotrexate (2.2 [IQR 1.6-3.1 years) versus thiopurines (6.6 [2.4-8.5]; p = 0.02). The overall adverse events rate was higher with thiopurines [20%] than methotrexate [12%; p <0.001], including three lymphoma cases in males, although the difference was not significant [4.8 vs 0 cases/10 000 treatment-years, respectively; p = 0.6]. Conclusion: Thiopurines demonstrated higher treatment durability than methotrexate but more frequent adverse events. However, disease outcomes were similar, partly due to more frequent escalation to biologics with methotrexate.