Part 1:
1. Choose a paper describing the development or validation of a measure of relevance in health disparities research (please give the full citation and/or upload the paper if that's possible).
Shavers VL. Measurement of socioeconomic status in health disparities research. J Natl Med Assoc. 2007;99(9):1013-1023.
Shavers (2007) explores socioeconomic status (SES) and details problems with SES as a construct and suggests important points to consider when using SES as a measure. I believe that this undertaking is vitally important given the ubiquity of SES in disparities research and in epidemiology in general encourages its unqualified acceptance.
2. What was the definition of the construct?
SES has taken several related, but not equivalent definitions over the years as noted in Dr. Shavers’s paper. The first definition comes from Mueller and Parcel (1981), which describes SES as “the relative position of a family or individual on a hierarchical social structure, based on their access to or control over wealth, prestige and power.” Shavers provides an alternative definition: “a broad concept that refers to the placement of persons, families, households and census tracts or other aggregates with respect to the capacity to create or consume good that are valued in our society.” I would argue that the second definition strives to be so inclusive that it becomes vague and weak. “Power and prestige” is a key component of SES as it is constructed in most applications. And as it is generally conceived, this power/prestige derives from economic advantage and/or occupying the privileged end of social/racial/ethnic hegemonies.
3. How did the authors provide evidence on the validity of the measure? Could you think of additional approaches to validating the measure?
Rather than provide evidence of validity of SES broadly, Dr. Shavers details the different ways that SES is measured, allowing readers to evaluate the validity (and threats to validity) of the whole construct. The validity of SES is threatened by the many divergent ways to define SES, including whether SES is described at the individual or aggregate level. Using a compositional approach to individual SES appears to have the best face validity because it is composed of the things that get to the root of “power and prestige” in society, particularly in economic terms. These factors include occupation (blue vs. white collar job) with or without income and education. Aggregate SES allowed more room for measurement error by relying on average and proxy measures applying to groups of people.
4. How did the authors provide evidence on the reliability of the measure? Could you think of additional approaches to evaluating the reliability of the measure?
Again, the author worked to critique assumptions of reliability of SES measures. For example, Shavers points out that SES is a cross-sectional measure of the a dynamic measure that attempts to capture factors which play out over the lifecourse. Reliability of SES may be particularly questionable when applied retrospectively since it will be “prone to selection bias as a consequence of…differential survival among study groups” for instance. The best way to test and evaluate reliability is comparing repeated measurement over time and in different groups to ensure that a hypothesized association between SES and the health outcome of interest is reproducible.
5. Describe the implications of a lack of measurement validity or reliability for future research applications.
When a measure is not valid or reliable, conclusions drawn from its use fail to describe the world the way researchers intend. Using an invalid measure can lead to finding spurious associations or no association when one exists. An unreliable measure of SES (or more precisely, the concept SES represents) will be a problem for reproducing findings and generalizing study results from one population to another. For example, if SES fails to capture the intended construct (for example by overweighting type of job and ignoring disenfranchisement of structural racism), it may fail to find a true association between lack of societal power/prestige and negative health outcomes.
Part 2:
1. Find a paper describing a health disparity (please give the full citation or, even better, upload the paper so everyone else can look at it too)
Hamoda RE, McPherson LJ, Lipford K, et al. Association of sociocultural factors with initiation of the kidney transplant evaluation process. Am J Transplant. 2020;20(1):190-203. doi:10.1111/ajt.15526
2. Summarize the construct and measurement of the dimension of disparity (e.g., racial inequalities?, SES inequalities?) and the outcome measured (e.g., self-rated health).
This paper examines “sociocultural factors” including medical mistrust, perceived racism in healthcare, and experienced discrimination to examine disparities between white and black patients with end-stage kidney disease (ESKD) referred for kidney transplant evaluation. The authors believe these concepts are related to structural racism and discrimination. They hypothesize that this construct mediates the relationship between structural racism and health-related disparities. The outcome was initiation of kidney transplant evaluation initiation after referral for transplant evaluation.
3. What is the evidence for the validity and reliability of the measures?
Instruments to measure the three sociocultural factors (medical mistrust, perceived racism in healthcare, and experienced discrimination) are described in the paper as “validated and researcher-developed” and include citations to original sources referring to those constructs. “Perceived racism in healthcare settings” was measured by the Racism Index, cited as having high internal reliability with Cronbach’s a=0.76. “Medical mistrust” was measured with the Medical Mistrust Index, also cited as having high internal reliability with Cronbach’s a=0.76. “Experiences of medical discrimination” were measured with the National Heart, Lung, and Blood Institute’s Jackson Heart Study Discrimination Form—no details on validity or reliability of that instrument were included in this paper.
4. What is the reference category used for the disparity measure (ie, who is the comparison group)? Why does this reference category make sense (or not) for this research question?
The reference category is white patients referred to kidney transplant. Since the authors hypothesize that structural racism would be responsible for an observed disparity, it makes sense to use white people as the reference group, since that group would not be harmed by structural racism (at least in the way in which it is conceived in modern American society).
5. How is the disparity quantified or measured? Is this an absolute or relative measure or are both provided? Describe which type of measure you would prefer for this research area, or, if both, why.
The disparity was reported as absolute differences in proportions of white and black patients initiating transplant workup after referral. Relative measures of the disparity were also produced using multivariable logistic regression to calculate the association of each sociocultural factor with the odds of initiating transplant evaluation. I agree with both relative and absolute measures being presented in this case. Absolute measures are also important for comparison and policy decisions, but the multivariable analysis is useful in showing the relative contribution of the various sociocultural constructs to the outcome.