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).
Bemanian A and Beyer KMM, Measures Matter: The Local Exposure/Isolation (Lex/ls) Metrics and Relationships between Local-Level Segregation and Breast Cancer Survival. Cancer Epidemiol Biomarkers Prev; 26(4), 2017.
2. What was the definition of the construct?
The black-to-white disparity in breast cancer survival is increasing and is thought that the racial residential segregation is a potential driver for this trend. The authors develop a set of new local segregation metrics named local exposure and isolation (Lex/Is). Using these new metrics, the authors explored associations between segregation and breast cancer survival in Milwaukee metropolitan area.
3. How did the authors provide evidence on the validity of the measure? Could you think of additional approaches to validating the measure?
The authors compared the new local isolation metric with two related metrics, the location quotient (LQ) and the index of concentration at extremes (ICE). Additional approaches to validating the measure would include exploring survival in other geographic areas and analyzing survival data for other cancers (predictive validity).
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?
The authors use multivariate cox proportional hazards regressions controlling for age, cancer stage, race/ethnicity and SES. Additional approaches would include inter-item consistency, test-retest reliability.
5. Describe the implications of a lack of measurement validity or reliability for future research applications.
A test with poor validity will not measure the disparity in survival data accurately. A test with poor reliability would result in very different survival data on future applications and this may affect the disparity in survival. It will be unethical to take substantive actions on the basis of the results which lack measurement validity or reliability.
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)
Banham D, Roder D, Farshid G, et.al. Disparities in cancer stage at diagnosis and survival of Aboriginal and non-Aboriginal South Australians. Cancer Epidemiol. 2017, 131-139.
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 compares cancer stages and stage specific survivals of Aboriginal and non-Aboriginal South Australians by retrospective analyses of cancer registry data. The study used 777 Aboriginal cases diagnosed between 1990-2010 matched to randomly selected non-Aboriginal cases by year of birth, year of diagnosis, sex and primary site of cancer.
Measurement: Racial inequalities between Aboriginal and non-Aboriginal South Australians
Outcome:Ccancer stages and Stage specific survivals.
3. What is the evidence for the validity and reliability of the measures?
To assess validity, the study used a test dataset of 970 Aboriginal cases and all other cases diagnosed between 1977-2010. Such disparity in these measures have previously been validated in four other studies involving Australian Aboriginal populations.
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?
Reference category: Non-Aboriginal South Australians. The reference category is appropriate as this group have similar geographical location and similar exposure to environmental conditions. Hence, the reference group closely matches the target group with respect to other covariates.
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 stage specific incidence of cancer was measured in the two groups. This is an absolute measure. In addition, odds ratios were calculated, which is a relative measure. Both the measures are appropriate. The absolute measure gives a sense of magnitude and the ORs gives a measure of the disparity between the two groups.