Background Studies suggest that racial discrimination impacts health via biological dysregulation due to continual adaptation to chronic psychosocial stress. Therefore, quantifying chronicity is critical for operationalising the relevant aetiological exposure and hence maximising internal validity. Using one of the most common discrimination scales in the epidemiological literature, we develop a novel approach for more accurately assessing chronicity and compare it with conventional approaches to determine whether coding influences differential exposure classification and associations with hypertension and depression among African American women.
Methods Data are from a socioeconomically diverse cross section of 208 mid-life African American women in Northern California (data collection: 2012–2013). Racial discrimination was assessed using the Everyday Discrimination Scale (α=0.95), and was coded using two conventional approaches: (1) situation-based coding: number of different situations ever experienced; (2) frequency-based coding: sum of Likert scale responses ranging from 'never' to 'almost everyday'; and (3) a new chronicity-based coding approach: sum of responses, weighted to capture annual chronicity (eg, ‘a few times a month’=3×12=36×/year). Outcomes are hypertension and depressive symptomatology (10-item Center for Epidemiologic Studies-Depression Scale).
Findings Exposure classification differed by coding approach, by up to 41%. There was a positive association between racial discrimination and hypertension prevalence for chronicity coding only (prevalence ratio=1.61, 95% CI 1.03 to 2.49). For depressive symptoms, a dose–response relationship of similar magnitude was observed for all three coding approaches.
Conclusion Scale coding is an important methodological consideration for valid exposure assessment in epidemiological research. Coding can impact exposure classification and associations with important indicators of African American women’s mental and physical health.
- blood pressure
- social epidemiology
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Correction notice This article has been corrected since it first published. The data collection year range has been corrected in the Methods section, a value has been corrected in table 1, and erronous text removed.
Contributors EM, first author, reviewed the literature, conceptualised the scientific question, designed and executed all statistical analysis (and takes responsibility for the integrity and validity of the analysis), and took primary responsibility for drafting the manuscript. MT assisted with the design of the analysis, data interpretation and drafting the manuscript. AR assisted with data interpretation and drafting the manuscript. MP assisted with concept and design of the study, was responsible for management of data collection and assisted with manuscript revisions. RH assisted with the design of the study and manuscript revisions. DC helped conceptualise the study and provided assistance with data interpretation and drafting the manuscript. AA, principal investigator, conceptualised the study, coordinated all logistics related to recruitment and data collection, assisted with the design of the analysis, data interpretation and drafting the manuscript.
Funding This work was supported by research grants from: University of California, Berkeley (UCB) Hellman Fund, UCB Population Center, UCB Research Bridging Grant, UCB Experimental Social Science Laboratory, Robert Wood Johnson Health and Society Scholars Program (UCB site), UC Center for New Racial Studies, and the UCB Institute for the Study of Societal Issues. EM was partially supported by grant GTDR14301469 from the Susan G Komen Foundation. AA was also partially supported by grant P60MD006902 from the National Institute on Minority Health and Health Disparities. MT was partially supported by grant UL1GM118985 from the National Institute of General Medical Sciences, and by a Ford Foundation Predoctoral Fellowship administered by the National Academies of Sciences, Engineering, and Medicine.
Disclaimer The funders had no involvement in the study design, data collection, analysis and interpretation of the data, writing of the report, nor the decision to submit the paper for publication.
Competing interests None declared.
Patient consent for publication Obtained.
Ethics approval The study was approved by the Committee for the Protection of Human Subjects at the University of California, Berkeley.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Per IRB approval, the data are restricted for transmission to those outside of the primary investigative team. All codes needed to replicate scale recoding and analysis will be provided and can be made publicly available.
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