Several principles are important in defining a moderator. First, the moderator must precede treatment. In our RCT, these psychosocial domains are baseline characteristics of subjects enrolled in the study. Second, the moderator must be uncorrelated with treatment choice. This will be the case in this RCT due to a 1:1 randomization, which should balance baseline characteristics between the two groups. Third, a moderator of treatment must have a differential effect of treatment for each level of the moderator. The treatment effect (e.g., active vs. comparator) must be shown to be greater for one level of the moderator (i.e. IPS-SE will show a greater effect size than standard VRP in subjects with a moderator present). Also, an index that combines these domains will be explored and formulated to identify subjects that may benefit to greater extent from IPS-SE.