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.
1. Is vitamin deficiency’s effect on the onset of early dementia, explained by SES?
In this question, SES (income) independently affects vitamin deficiency and the onset of dementia. Income can limit food options, that is, opting for unhealthy, fast food options that result in a deficiency of a nutrient rich diet. Low income due to chronic unemployment is linked to the onset of dementia, although the biological pathway is unclear. Therefore, SES confounds the causal relationship between vitamin deficiency and early dementia.
2. What is the impact of race/ethnicity on the likelihood of undegoing an invasive procedure to remove their fibroids?
Black women have a higher likelihood of having a greater number and volume of fibroids, as well as experience more severe symptoms as a result of them. Black women of lower SES, specifically education, may be unable to understand or seek alternative minimally invasive options, compared to those of higher SES. In this context, SES is an effect modifier of the relationship between race ethnicity and invasive surgical procedures.
3. Is diet’s effect on glucose levels (diabetes), explained by changes in SES?
Here, SES mediates the relationship between diet and diabetes, as those of higher SES likely have greater access to healthy foods, gym memberships, or overall understanding of the importance of healthy eating habits.
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.
After reading the Diez-Rouz article, I was intrigued by the multilevel analysis approach in epdimeologic work. An association of interest in my subject-knowledge is the relationship between mean neighborhood income, a contextual variable, on the experience of symptom severity among women suffering from uterine fibroids. Using an area based measure of access and deprivation can contextualize the experiences of women from different backgrounds, in relation to their surrounding environment. Mean neighborhood income can be retrived from the Census, and upon collaboration with UCSF/SF general women receiving care for fibroids they would take the Uterine Fibroid Symptom and Health-Related Quality of Life Questionnaire (UFS-QOL). A cross-sectional analysis of the information would then be completed to study this relationship.