The purpose of the present study was to (1) identify characteristics of patients with Crohn disease at baseline and at week 8 of ustekinumab therapy (before the start of subcutaneous maintenance therapy) that predict long-term remission on ustekinumab therapy using C-reactive protein (CRP) level as a biomarker of disease activity, and (2) evaluate the incremental advantage of using these predictors compared with drug level alone. Here, CRP is linked to Crohn disease.