1. Give an example of a research question for investigating racial/ethnic health disparities where: [1] SES is a confounder; [2] SES is an effect modifier; [3] SES is a mediator. Briefly discuss the interpretations/implications of each approach as it relates to understanding health disparities by race/ethnicity.
SES is a confounder if one were to ask what the effect is of insurance status on hospital admission rates. One’s socioeconomic status (related to income, employment status) will affect whether one is insured but may also affect hospital admission rates as SES has independent influence on one’s health.
SES serves as an effect modifier (affecting the outcome but not the predictor) when asking about the rate of follow-up for patients who have survived Hodgkin’s lymphoma. Although there is not a clear association between SES and Hodgkin’s lymphoma, one’s socioeconomic status will affect the kind of post-treatment care, access to transportation, knowledge about follow-up that will influence this rate.
SES is a mediator when investigating a question of how age affects insurance status. One’s age will have a causal relationship with SES, which will have a causal relationship with insurance status.
When looking at race/ethnicity, there are much more overarching relationships. Race/ethnicity has an effect on SES in addition to independently having effects on some of the above predictors and/or outcomes. There have been a number of example frameworks in how to address this role, and in many ways race and ethnicity serve as an integral variable (as described by Diez-Roux). One must identify this relationship a priori in asking one’s research question or risk missing or misidentifying relationships that arise in the results.
2. Describe a potential effect modifier, mediator, or contextual variable (for definition of contextual variable, see Diez-Roux reading) for an association of interest to you and relevant to health disparities. For example, for investigating the association between education and hypertension, I might be interested in evaluating whether the association between years of education and hypertension is different for Black men than for White men. Describe how you would study whether this relationship exists.
I am interested in the role of English language proficiency and the effect on sedation practices in the ICU. A potential effect modifier might be age as it may not affect language proficiency, but it will still likely influence the amount of sedation administered. I would try to look at the relationship of age to sedation practices before including age with language proficiency in a mixed effects model.