Impact of 5-aminosalicylic acid intolerance on progression to difficult-to-treat ulcerative colitis: a retrospective cohort study.

Overall intolerance was independently associated with an increased risk of D2T progression (subdistribution hazard ratio [sHR] 2.07, 95% confidence interval [CI] 1.14-3.75), but not with colectomy.

Landmark analyses showed that 5-ASA users at 90 or 365 days exhibited a lower cumulative incidence of D2T progression than non-users.

Furthermore, following advanced therapy initiation, overall 5-ASA intolerance was not associated with secondary failure of ≥ 2 mechanisms of action, whereas acute intolerance syndrome remained independently associated with this outcome.