Non-Hispanic Black Americans Diminished Protective Effects of Educational Attainment and Employment against Cardiometabolic Diseases: NHANES 1999-2016

Research Article

Austin J Public Health Epidemiol. 2021; 8(4): 1109.

Non-Hispanic Black Americans’ Diminished Protective Effects of Educational Attainment and Employment against Cardiometabolic Diseases: NHANES 1999-2016

Zare H1,2* and Assari S3,4,5

1Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, USA

2University of Maryland Global Campus, Health Services Management, USA

3Marginalization-Related Diminished Returns (MDRs) Research Center, Charles R Drew University of Medicine and Science, USA

4Department of Family Medicine, Charles R Drew University of Medicine and Science, USA

5Department of Urban Public Health, Charles R Drew University of Medicine and Science, USA

*Corresponding author: Hossein Zare, Department of Health Policy and Management, Johns Hopkins Center for Health Disparities Solutions, Johns Hopkins Bloomberg School of Public Health, University of Maryland Global Campus, Health Services Management, 624 North Broadway, Hampton House, Room #337, Baltimore, Maryland, 21205, USA; Email: hzare1@jhu.edu

Received: August 26, 2021; Accepted: September 27, 2021; Published: October 04, 2021

Abstract

Background: While Socioeconomic Status (SES) indicators such as educational attainment and employment are among the major drivers of health and illness, the health returns of SES indicators may differ across racial groups. Built on the Marginalization-Related Diminished Returns framework (MDRs) that refers to weaker health effects of SES indicators for marginalized and minoritized groups than non-Hispanic White people, we conducted this study with two aims: First, to test the association between educational attainment and employment with Cardio Metabolic Diseases (CMDs), and second, to test racial variations in these associations.

Methods: This cross-sectional study used the National Health and Nutrition Examination Survey (NHANES 1999-2016) data. Participants included 29,230 adults who were either non-Hispanic White or non-Hispanic Black. We measured the following: race, demographic factors (age and sex, and marital status), SES (educational attainment and employment), behaviors (smoking, drinking, and exercise), health insurance, and CMDs (diabetes, stroke, hypertension, and congestive heart failure). Weighted Poisson regression models were used in Stata to adjust for the complex sample design of the NHANES. Models without and with interactions were performed in the pooled sample. We also ran racestratified models.

Results: Overall, high educational attainment and employment showed inverse associations with some CMDs. As documented by statistical interactions between race and our SES indicators, we observed weaker inverse associations between educational attainment and employment with some CMDs. Racestratified models also confirmed our main analysis; however, the results varied across CMD conditions.

Conclusion: We observed that SES indicators such as educational attainment and employment have differential associations for racial groups. Compared to non-Hispanic White people, non-Hispanic Black people remain at CMDs risk across the full SES spectrum. This finding is in line with the MDRs framework and may be due to the structural racism, social stratification, and marginalization of non-Hispanic Black Americans.

Keywords: Cardiometabolic disease; Diabetes; Stroke; Hypertension; Congestive heart failure; Education; Employment; Socioeconomic status; Population groups

Background

As shown and discussed by Marmot [1,2], Hayward [3- 5], Link and Phelan [6], Ross and Miroswky [7-9], and others [10], Socioeconomic Status (SES) indicators such as educational attainment and employment are among the primary drivers of health, including but not limited to Cardio Metabolic Diseases (CMDs) such as diabetes, hypertension, stroke, and heart disease [11]. However, a growing body of research by Kaufman [12], Braveman [13], Shapiro [14,15], Williams [16,17], Ceci [18], and Navarro [19-21] has shown that SES indicators may not be comparable across racial groups; thus, the health effects of SES indicators are not equal across various social groups. To describe this phenomenon, Kaufman referred to a poor overlap between SES of racial groups as well as residual confounding of race due to unmeasured SES indicators [12]. Navarro mentions that “race and SES”-not “race or SES”-influence health disparities, which refers to the complex interplays between race and SES [19-21]. Ceci highlighted the differences between the Haves and the Have- Nots in their capacity to uptake SES indicators [18]. His work argues that when resources become available, Have-Nots may be at a relative disadvantage for turning those resources into outcomes [18]. Assari recently described this phenomenon as a Marginalization-Related Diminished Returns (MDRs) phenomenon [22,23].

The MDRs phenomenon refers to weaker economic and health effects of SES indicators, particularly educational attainment and employment, for marginalized communities, particularly racial minorities, than for US-born heterosexual non-Hispanic Whites [22,23]. These MDRs are also reported by Ferarro [24], Thorpe [25-27], Hudson [28-30], and others [31]. These studies have all documented weaker effects of SES on health for non-Hispanic Blacks than for non-Hispanic Whites. While other racial and ethnic minorities may also show some similar patterns, these MDRs are most robust for comparing non-Hispanic Blacks than for non-Hispanic Whites [22,23].

While these MDRs hold across SES indicators and health outcomes, they are best described for parental education, education, and income on mortality, self-rated health, and substance use. Less is known about the MDRs of other education and employment on Cardiometabolic Diseases (CMDs). This is important because these MDRs may be more robust for more distant (e.g., education) than proximal social determinants (e.g., employment). This is probably because more social processes can hinder the effects of educational attainment than employment on health [32]. In other terms, by the time individuals have secured employment, they have probably overcome some of the societal injustices. However, educational attainment may not result in the same employment for non- Hispanic Black and non-Hispanic White people because of labor market discrimination [33]. As such, we expect stronger MDRs for educational attainment than for employment. Besides, we expect that some of the MDRs of education to be due to differential employment opportunities, thus controlling for employment may reduce the significance of MDRs due to educational attainment [32].

MDRs framework [22,23] can be regarded as a paradigm shift in health disparities research. While these MDRs are not unknown [22,23] and well-established for education of non-Hispanic Blacks [34,35], they are different from most of the existing literature that has traditionally focused on the role of poverty and low SES as the mechanism for racial health inequalities. Moreover, these MDRs are a paradigm shift because they: (a) seek how economic and health effects of available SES indicators vary across non-Hispanic Whites and non-Blacks, (b) explore racial disparities across the full SES spectrum and allow SES returns to vary by race, (c) use a moderated-mediation rather than a mediation model, (d) test non-linear and non-additive effects of race and SES, which are more realistic than universal average effects, and (e) explain why the racial health gap may widen rather than narrow as SES increases [22,23].

Aims

In response to the gap in the literature, we conducted a secondary multilevel analysis of the National Health and Nutrition Examination Survey (NHANES) to determine the associations between education and employment and CMDs by race. First, we hypothesize inverse associations between educational attainment and employment with CMDs. Second, built on the MDRs framework, we hypothesize that the inverse associations between educational attainment and employment with CMDs would be weaker for non-Hispanic Black than for non-Hispanic White adults. As a result, we expect a high prevalence of CMDs in non-Hispanic Blacks across educational attainment and employment levels. This will be in contrast to non- Hispanic White people for whom the prevalence of CMDs would be low in highly educated and employed individuals.

Materials and Methods

We used the National Health and Nutrition Examination Survey (NHANES) data between 1999-2016 [36]. The NHANES is a crosssectional survey that provides nationally representative health and nutritional status estimates for the US population. The response rate for this data between 1999-2016 reported 73.2% [37,38]. For this analysis, we included 29,230 individuals who were 20 years old and older. From this number, 31% were non-Hispanic Black, and 69% were non-Hispanic White.

Outcome variable

We used five outcomes. The first four outcome variables included stroke, hypertension, diabetes, and Congestive Heart Failure (CHF). The last outcome was the presence of any CMDs, regardless of their type. We used a dummy variable for each chronic condition if the condition had been diagnosed by a doctor or any other health professional. Following the American Heart Association Guidelines, hypertension has been defined as systolic blood pressure ≥140mmHg or diastolic blood pressure ≥90; the AHA modified hypertension 2017 guidelines are the most recent [39]. But, the NHANES data was collected before 2017. Therefore, in addition to the four mentioned conditions, we created a composite measure, including any of the four conditions.

Main independent variable

The main independent variables of interest were the educational level and employment. Education was defined as a categorical variable (less than high school graduate, high school graduate, or general equivalency diploma, more than high school education or some college and above). Employment was a dummy variable (=1, If the individual was working at a job or business or with a job or business but not at work and =0, if looking for a job or not working at a job or business).

Covariate

For the demographic variables, we included age (years), sex, and marital status (1 = married, 0 = otherwise). For socioeconomic status, we included income ($0-$34,999, 35,000-$74,999 and ≥75,000). We also included a dummy variable: having health insurance (1 = yes; 0 = no). We also controlled for health behavior, including smoking (never smoked, a former smoker or current smoker), drinking (never drink, former drinker, or current drinker), and physical activity (vigorous activity).

Race

The moderator was racial/ethnic group. This was a dichotomous variable (non-Hispanic White = 0 and non-Hispanic Black =1).

Analytic strategy

We used descriptive analysis to compare the mean and proportional differences between non-Hispanic White and non- Hispanic Black people for all four conditions. Demographics, SES, and health behaviors were evaluated using unequal variances t-tests and chi-square. We used the weighted modified Poisson regression analysis [40-42] to produce Prevalence Ratios (PR) and the corresponding 95% confidence intervals (CI) [40,41]. For the first set of analyses, we ran sets of adjusted models. To find the impact of education and employment interaction on CMDs, we ran the 2nd set of analyses with two interactions between race/ethnicity and education and race/ethnicity and employment status. Finally, for the last set of analyses and because the interaction between race/ethnicity and education and race/ethnicity and employment status were significant (p<0.001), we stratified the analyses by race. All analyses were weighted using the NHANES individual-level sampling weights for 1999-2016 (8 waves of data) to make the estimates representative at the national level for the US civilian population [43]. We considered P-values <0.05 as statistically significant, and all tests were twosided. We used STATA statistical software version 15 to perform all analyses.

Results

Descriptive data

A total of 29,230 individuals entered our analysis. From all participants, 12.89% (n = 9,023) were non-Hispanic Black and 77.11% (n = 20,207) were non-Hispanic White. The prevalence was diabetes (7.76%), stroke (2.68%), hypertension (14.13%), CHF (2.37%), and any CMDs (22.29%). The mean age of the participants was about 49 years (SD = 11). Of all the participants, 64.87% were employed and 65.11% had education more than a high school degree (Table 1).