Background: Data about the efficacy of topical therapy with tacrolimus in patients with ulcerative colitis (UC) is scarce. Therefore, this study aimed to evaluate topical tacrolimus's effectiveness and adverse events in a real-world setting.

Methods: A multicenter retrospective study was conducted at 27 hospitals across Spain. Adult patients with UC who had received suppositories, enemas or tacrolimus ointment due to persistent clinical or endoscopic activity despite topical mesalamine and/or steroids from January 2009 to January 2023 were included. The primary outcome was clinical response at week 8.

Results: A total of 148 patients were included. Sixty-nine patients (46.6%) received suppositories, 78 (52.7%) received enemas, and one patient used an ointment (0.7%). Clinical remission was achieved in 43 (33.6%), and clinical response in 76 (59.4%) patients at week 4. The primary outcome was achieved in 87 (67.4%), and clinical remission was achieved in 61 patients (47.3%) at week 8. Median tacrolimus trough level was 3.4 ng/mL(IQR 1.5-6.7) at week 4 and 2.9 ng/mL (IQR 1.5-6) at week 8. After a median follow-up of 55.1 weeks (IQR 40.6-55.7) since starting topical tacrolimus, 63 (42.6%) patients needed treatment escalation other than tacrolimus during the follow-up period, with a 1-year risk of treatment escalation of 46.2% (95% CI 37.3-56.1%). Adverse events were detected in 21 patients (14.2%), with twelve graded as mild and nine moderate (42.6%).

Conclusions: Topical tacrolimus is an effective therapy and could be considered in distal UC patients before initiating other advance therapies when endoscopic activity remains.