The 4-week follow-up in the GAIN trial seems short, but it is adequate to detect early improvement. In infliximab-naive patients with Crohn disease (CLASSIC I [Clinical Assessment of Adalimumab Safety and Efficacy Studies as Induction Therapy in Crohn's Disease I] study (2)), the same adalimumab induction regimen and follow-up, compared with placebo, resulted in a CDAI score decrease of 70 points or more and remission rates of 59% versus 37% and 36% versus 12%, respectively. Adalimumab on the same schedule but at a lower dose caused a primary response in 58% of patients at 4 weeks in a study of adalimumab maintenance dosing (10). On the other hand, we lack important information about the infliximab-experienced patients in the GAIN trial. We do not know the dosing schedule of infliximab; disease activity before infliximab treatment began, at the time of response, and at the time of loss of response; and the cumulative dose of infliximab before the loss of response or the development of intolerable side effects. Without this knowledge, we are left to wonder whether the GAIN trial investigators introduced a bias against adalimumab by enrolling patients who otherwise would have been classified as primary nonresponders. Conversely, the authors might have included patients who would have responded well to infliximab if treatment had not been stopped because of otherwise manageable infusion reactions, which could introduce a bias favoring adalimumab. Finally, the investigators did not compare adalimumab responses in patients with larger or smaller cumulative infliximab doses. Without this subgroup analysis, we are uncertain about the generalizability of the GAIN trial results.