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).
Lee S.-Y. D., Stucky B.D., Lee J. Y. et al. Short assessment of health literacy–Spanish and English: A comparable test of health literacy for Spanish and English speakers HSR 2010 August;45(4):1105–20. Pub Med ID (PMID): 20500222
2. What was the definition of the construct?
In the paper, the authors define health literacy as ‘‘capacity to obtain, process, and understand health information and services needed to make appropriate health decisions’’. The instrument is called the Short Assessment of Health and Literacy-Spanish and English (SAHLS&E). They developed and tested a health literacy test for Spanish and English speakers. In developing the tool, they started with the 66 medical terms from the Rapid Estimate of Adult Literacy in Medicine (REALM) and eventually narrowed down to 18 items through a series of item response theory (IRT) analysis. For the validation of the construct, examinees are asked to read aloud each of the 18 medical terms and then associate each term to another word similar in meaning to demonstrate comprehension.
3. How did the authors provide evidence on the validity of the measure? Could you think of additional approaches to validating the measure?
Validation of the instrument, the Short Assessment of Health and Literacy-Spanish and English, involved testing and comparing the instrument with other health literacy instruments in a sample of 201 Spanish-speaking and 202 English-speaking subjects recruited from Ambulatory Care Centre at the University of North Carolina Healthcare System. Verification was based on the correlation between the REALM score and the association test score.
For the construct validity of the comparable test, they performed a few analyses: 1) correlation with the Spanish version of the test to the Short Assessment of Health and Literacy-Spanish and Test of Functional Health Literacy in Adults (TOFHLA); 2) correlating the English version of the test to the REALM and English TOFHLA; 3) correlating the examinee’s test score to his/her years of schooling. In the study, SAHL-S was highly correlated with SAHLSA (r=0.88, p<0.05) and Spanish TOFHLA (r=0.62, p<0.05) in the Spanish-speaking sample. SAHL-E also had high correlations with REALM (r=0.94, p<0.05) and English TOFHLA (r= 0.68, p<0.05) in the English-speaking sample. Significant correlations were also found between SAHL-S&E and years of schooling in both the Spanish- and English-speaking samples (r =0.15, p<0.05 and r=0.39, <0.05, respectively).
SAHL-S&E displayed satisfactory reliability of 0.80 and 0.89 in the Spanish- and English-speaking samples, respectively. IRT analysis indicated that the SAHL-S&E score was highly reliable for individuals with a low level of health literacy.
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?
For reliability, they: 1) calculated Cronbach a for each version of the test. Cronbach a, a measure of internal reliability, indicates the extent to which the reliability of the test scores was similar across samples; 2) using an IRT-based approach, test information was computed. Test information reflects how reliably (or precisely) the SAHLS&E items measure health-related reading ability across the range of literacy.
5. Describe the implications of a lack of measurement validity or reliability for future research applications.
Health literacy is a significant contributor to disparities in accessing health information and navigating the health care system. Inadequate health literacy increases challenges of understanding health information and following medical instructions, poor disease/self management knowledge, underuse of preventive service and routine physician visits, increased hospitalizations and medical costs, and high mortality rates. Identifying people with inadequate health literacy is hard because age, educational attainment and self-reported literacy skills do not reliably reflect a person’s health literacy level. Not having a valid or reliable measure can worsen disparities in accessing health information and health care.
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)
Gomez SL, Quach T, Horn-Ross PL, Pham JT, Cockburn M, Chang ET, Keegan TH, Glaser SL, Clarke CA. Hidden breast cancer disparities in Asian women: disaggregating incidence rates by ethnicity and migrant status. Am J Public Health. 2010 Apr 1;100 Suppl 1:S125-31. doi: 10.2105/AJPH.2009.163931. Epub 2010 Feb 10.
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).
Construct: Racial/ethnic disparities (ethnicity and immigrant status obtained from California Cancer Registry, which collects information on patient race/ethnicity and birthplace from hospital medical records, which is obtained primarily through self-report; by assumption of hospital personnel; on inference from other information including race/ethnicity of parents, maiden name, surname and birthplace; and from death records.
Outcome: breast cancer incidence rate (data from California Cancer Registry- diagnosed with primary invasive breast cancer via ICD coding).
3. What is the evidence for the validity and reliability of the measures?
Generally, self-report is not ideal or perfect, but when classifying race/ethnicity, will capture what people perceive to be their race/ethnicity. The study however, also included assumption of hospital personnel, which definitely can lead to misclassification bias. To obtain information on nativity, the study used 1) registry data from hospital medical records and 2) statistical imputation of immigrant status using the first 5 digits of patient’s social security number; these measures likely increased the validity and reliability of nativity.
· Ethnicities included in the study were Chinese, Japanese, Filipina, Korean, South Asian, Vietnamese
· Foreign born vs US born
The outcome was obtained via ICD coding, which for a diagnosis such as primary invasive breast cancer, is probably pretty accurate., since diagnosis of cancer is usually confirmed with pathology.
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?
Comparison group: Non-Hispanic Whites
This research question tries to disaggregate data on breast cancer disparities among various Asian ethnicities. I don’t think Non-Hispanic Whites makes sense as the reference category. I agree with comparing the aggregated Asian group to the disaggregated groups. The study also includes incidence rate and incidence rate ratios for Asians at an aggregated level, comparing foreign born-and US-born, with foreign born as the reference group.
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.
This disparity is measured both using incidence rate which is an absolute measure and incidence rate ratio which is a relative measure. I think it’s nice to have both because the absolute measure gives a better sense of the importance and magnitude of breast cancer incidence while the ratio gives you a better relative measure and may be easier for to communicate to patients, the public, etc.