Does long-term efficacy differ between infliximab and adalimumab after 1 year of continuous administration?

Although biologics are important inflammatory bowel disease therapies, loss of response (LOR) remains problematic. We evaluated LOR to biologics in our Crohn disease (CD) patients receiving biologics. Of 137 biologic-treated CD patients, 68 continuously receiving the same biologic type for at least 1 year were divided into 2 groups: infliximab (IFX) (n = 39) and adalimumab (ADA) (n = 29). Clinical courses were compared at biologic introduction and at 1 year. Both groups were retrospectively analyzed for LOR at and beyond 1 year after biologic introduction (study endpoint). Patients were then divided into LOR and non-LOR groups to identify factors predicting LOR. At 1 year after biologic introduction, decreases in CD activity index were 94 ± 105 in the IFX and 102 ± 89 in the ADA group, not significantly different. Blood test data did not differ between these groups. LOR occurred in 14 IFX and 5 ADA group patients. Event-free rates at 5 years after biologic introduction were 62% in the IFX and 61% in the ADA group. Patients achieving clinical remission 1 year after biologic introduction accounted for 69% of the IFX and 90% of the ADA group, while respective rates of secondary LOR at 5 years were 32% and 26%. C-reactive protein (CRP) at biologic introduction (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.04-2.06; P = .02) and age at CD onset (OR, 1.1; 95% CI, 1.01-1.20; P = .03) predicted LOR. As to IFX and ADA efficacies after 1 year of administration, there were no significant differences in event-free rates for the 5 years after biologic introduction or the secondary LOR rate. CRP at biologic introduction and age at CD onset predicted LOR.