DOP54 Real-world effectiveness of thiopurine monotherapy in Crohn’s Disease: Is there still a place for thiopurines in the biological era?

Abstract

Abstract Background In current guidelines, thiopurines are still recommended as first-line maintenance therapy for patients with Crohn’s disease (CD). Due to their lack of immunogenicity, oral administration route and low costs, thiopurines are an attractive first-line treatment option. However, in recent studies the position of thiopurine monotherapy in CD has been questioned as a result of relatively lower overall effectiveness rates compared to ulcerative colitis. Real-world long-term effectiveness data substantiating the use and position of thiopurines in CD management remain sparse. We assessed long-term effectiveness of thiopurine monotherapy in CD using the population-based IBD South-Limburg (IBDSL) cohort. Methods All CD patients in the IBDSL cohort starting thiopurine monotherapy as first-line maintenance therapy between 1991–2014 were included. Thiopurine monotherapy was defined effective if either: (1) no escalation to biological treatment, (2) no course of corticosteroids, (3) no resective surgery or, (4) no hospitalization for active disease was required whilst on thiopurine treatment. Patients with early treatment discontinuation (i.e. <3 months) were identified, including reason of discontinuation. Long-term effectiveness was assessed adjusting for differences in follow-up between patients using Kaplan-Meier analysis. Potential risk factors for therapy failure were identified using Cox regression. Results In total, 643/1162 (55.3%) CD patients (median follow-up: 8.5 years IQR 5.0–13.2) received first-line thiopurine monotherapy after a median of 9.7 months (IQR 3.2–31.3) after diagnosis. Therapy was discontinued within three months in 164 patients (25.5%), mainly due to adverse events [Figure 1]. Thiopurine monotherapy was effective for the duration of treatment in 229/479 (35.6%) patients, corresponding to estimated effectiveness rates of 62.9%, 43.9% and 31.2% after 1, 5 and 10 years, respectively [Figure 1–2]. No significant difference in effectiveness was observed after stratifying for era of thiopurine initiation (pre-biological (1991–1998) vs. biological (>1999) era, p=0.84). Factors associated with thiopurine failure were stricturing disease (aHR 1.41, 95%CI 1.01–1.96) and upper GI involvement (aHR 1.52, 95%CI 1.02–2.28) at diagnosis. During follow-up, 40/229 patients with a durable response discontinued treatment due to quiescent disease. Of these, 35 patients (87.5%) remained without treatment 24 months after discontinuation. Conclusion Real-world data from this population-based study demonstrate that thiopurine monotherapy remains an effective and durable first-line treatment option for CD, even in the biological era. These results should be considered in the ongoing discussion regarding the position of thiopurine therapy.