Combination therapy is not associated with improved rates of clinical or endoscopic remission in patients with inflammatory bowel disease treated with ustekinumab or vedolizumab: a retrospective study.

Background: Management of inflammatory bowel disease (IBD) involves biological agents, often in combination with thiopurines or methotrexate. The aim of our study was to compare clinical and endoscopic outcomes in IBD patients treated with vedolizumab or ustekinumab, as monotherapy or in combination with thiopurines or methotrexate.

Methods: We conducted a retrospective cohort study of all patients aged ≥18 years with a diagnosis of ulcerative colitis or Crohn's disease, commenced on vedolizumab or ustekinumab between October 2015 and March 2022. Primary outcome was clinical remission or response calculated by partial Mayo score (remission: <3; response: improvement >1) for ulcerative colitis or Harvey-Bradshaw index (<5, >2 respectively) for Crohn's disease over 1 year. Secondary endpoints were treatment failure, relapse, endoscopic remission at 1 year. Statistical analysis was done using 2-sample Student's and chi-square tests.

Results: A total of 159 IBD patients were included in the study, 85 (53%) on vedolizumab and 74 (47%) on ustekinumab. For those on vedolizumab, 61 (72%) patients had ulcerative colitis, and 24 (28%) has Crohn's disease. All patients on ustekinumab had Crohn's disease. Mean disease duration in was 9.4 and 13.5 years respectively. There was no difference in clinical response or remission for vedolizumab or ustekinumab monotherapy compared to combination therapy at 1 year. There was also no difference in treatment failure, relapse or endoscopic remission.

Conclusion: Combining vedolizumab or ustekinumab with an immunomodulator is not superior to monotherapy in terms of clinical response or endoscopic remission up to 1 year in IBD.