Abstract
In the accompanying commentary, Rose and van der Laan (Am J Epidemiol. 2014;179(6):663-669) criticize the relative excess risk due to interaction (RERI) measure, the use of additive interaction, and the weighting approach we developed to assess RERI with case-control data. In this commentary, we note some of the advantages of using additive measures of interaction, such as RERI, in making decisions about targeting interventions toward certain subgroups and in assessing mechanistic interaction. We discuss the relationship between Rose and van der Laan's estimator for case-control data and the one we had previously proposed. We also develop a new doubly robust estimator for determining the RERI with case-control data when the prevalence or incidence of the outcome is known.