Stopping 5-aminosalicylates in patients with ulcerative colitis starting biologic therapy does not increase the risk of adverse clinical outcomes: analysis of two nationwide population-based cohorts.

Objective: The benefit of continuing 5-aminosalicylate (5-ASA) in patients with ulcerative colitis (UC) who initiate anti-tumour necrosis factor-alpha (anti-TNF) biologics is unknown. We aimed to compare clinical outcomes in patients with UC already on 5-ASA who started anti-TNF and then either stopped or continued 5-ASA.

Design: Our primary outcome was any adverse clinical event defined as a composite of new corticosteroid use, UC-related hospitalisation or surgery. We used two national databases: the United States (US) Truven MarketScan health claims database and the Danish health registers. Patients with UC who started anti-TNF after having been on oral 5-ASA for at least 90 days were included. Patients were classified as stopping 5-ASA if therapy was discontinued within 90 days of starting anti-TNF. We performed multivariable Cox regression models controlling for demographics, clinical factors and healthcare utilisation. Adjusted HRs (aHR) with 95% CI are reported comparing stopping 5-ASA with continuing 5-ASA.

Results: A total of 3589 patients with UC were included (2890 US and 699 Denmark). Stopping 5-ASA after initiating anti-TNF was not associated with an increased risk of adverse clinical events in the U.S. cohort (aHR 1.04; 95% CI 0.90 to 1.21, p=0.57) nor in the Danish cohort (aHR 1.09; 95% CI 0.80 to 1.49, p=0.60). Results were similar in sensitivity analyses investigating concomitant immunomodulator use and duration of 5-ASA treatment before initiating anti-TNF.

Conclusion: In two national databases, stopping 5-ASA in patients with UC starting anti-TNF therapy did not increase the risk of adverse clinical events. These results should be validated in a prospective clinical trial.