Population-based cohort study on comparative effectiveness and safety of biologics in inflammatory bowel disease.

Background: The comparison of effectiveness and safety of anti-tumor necrosis factor-alpha agents for the treatment of inflammatory bowel disease (IBD) is relevant for clinical practice and stakeholders.

Objective: The objective of this study was to compare the risk of abdominal surgery, steroid utilization, and hospitalization for infection in Crohn's disease (CD) or ulcerative colitis (UC) patients newly treated with infliximab (IFX) or adalimumab (ADA).

Methods: A retrospective population-based cohort study was performed using health information systems data from Lazio region, Italy. Patients with CD or UC diagnosis were enrolled at first prescription of IFX or ADA during 2008-2014 (index date). Only new drug users were followed for 2 years from the index date. IFX versus ADA adjusted hazard ratios were calculated applying "intention-to-treat" approach, controlling for several characteristics and stratifying the analysis on steroid use according to previous drug utilization. Sensitivity analyses were performed according to "as-treated" approach, adjusting for propensity score, censoring at switching or discontinuation, and evaluating different lengths of follow-up periods.

Results: We enrolled 1,432 IBD patients (42% and 83% exposed to IFX for CD and UC, respectively). In both diseases, treatment effects did not differ in any outcome considered, and sensitivity analyses confirmed the results from the main analysis.

Conclusion: In our population-based cohort study, effectiveness and safety data in new users of ADA or IFX with CD or UC were comparable for the outcomes we tested.