The investigators have proposed to investigate whether serum cytokines can predict the outcomes to ustekinumab treatment in patients with Crohn’s disease. However, the methods of this analysis are not clear. The investigators have examined that receiver operating curves (ROC) will be generated for each outcome of interest: 1) CDAI less than 150 at week 8, week 16, week 52 and 2) CDAI decrease of 100 or more, and that the AUCs will be compared between groups. However, the groups are not clearly defined. I presume the two groups are those that received ustekinumab and those that received placebo. Correct? But also, how will this assess the association of serum cytokines and outcomes of treatment? Is there a plan to use a measure of serum cytokines that has not been described? Nor are any other variables proposed for use in this analysis. Please clarify.