Diminished Protective Effects of Education, Income and Employment against Obesity Risk in Black Women at Reproductive Age: National Health and Nutrition Examination Survey (NHANES 1999-2016)

Research Article

J Community Med Health Care. 2022; 7(1): 1053.

Diminished Protective Effects of Education, Income and Employment against Obesity Risk in Black Women at Reproductive Age: National Health and Nutrition Examination Survey (NHANES 1999-2016)

Assari S1,2,3* and Zare H4,5

1Marginalization-Related Diminished Returns (MDRs) Research Center, Charles R Drew University of Medicine and Science, Los Angeles, California, USA

2Department of Family Medicine, Charles R Drew University of Medicine and Science, Los Angeles, California, USA

3Department of Urban Public Health, Charles R Drew University of Medicine and Science, Los Angeles, California, USA

4Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA

5University of Maryland Global Campus, Health Services Management, Adelphi, Maryland, USA

*Corresponding author: Shervin Assari, Marginalization-Related Diminished Returns (MDRs) Research Center, Department of Family Medicine, Charles R Drew University of Medicine and Science, Los Angeles, California, USA

Received: December 24, 2021; Accepted: January 31, 2022; Published: February 07, 2022

Abstract

Background: Socioeconomic status (SES) indicators protect individuals and populations against health problems such as obesity. Marginalizationrelated Diminished Returns (MDRs), however, refer to the weaker economic and health returns of education, employment, and income for Black than the returns for White people.

Aims: To test the effects of three major SES indicators, namely educational attainment, employment, and income, on obesity for women at reproductive age, and to test variation in these associations by race.

Methods: We used cross-sectional data from the National Health and Nutrition Examination Survey (NHANES). Sample was limited to non-Latino White and Black women at reproductive age (age between 20 and 44). Analytical sample was composed of 5237 women. Survey regressions were used to test the effects of education, employment, and income (independent variables) on obesity (dependent variable) and by race (moderator).

Results: Overall, educational attainment and income were inversely associated with odds of obesity in our sample, however, we found significant interactions indicating that the effects of education, employment, and income were all weaker for Black than White women.

Conclusions: In line with MDRs, and probably due to structural racism, social stratification, labor market discrimination, and different food options, obesity remains higher than expected in highly educated, employed, and highincome Black women, a pattern that is not seen in White women. Black middleclass women at reproductive age remain at risk for obesity. To eliminate racial disparities in perinatal outcomes, we need to go beyond low SES and address the perinatal needs of middle-class Black women, for whom obesity remains a health risk.

Keywords: Obesity; Body mass index; Race; Racism; Social determinants; Socioeconomic status

Background

While socioeconomic status (SES) indicators such as educational attainment, employment, and income are among major protective factors of individuals and populations against disease and illness [1- 4], recent studies have shown that SES indicators may show that these health effects are weaker for non-Hispanic Black than non-Hispanic White people. This phenomenon is known as Marginalization-related Diminished Returns (MDRs), also called Minorities’ Diminished Returns (MDRs) or Blacks’ Diminished returns [5,6]. This framework suggests that racialization and minoritization of may alter the relevance of SES indicators and social determinants of health (SDoH) [7-12] and fundamental causes [13-16] for health across social groups. Most of this literature, however, is on education rather than employment and income.

Marginalization-related Diminished Returns (MDRs) [5,6] can be defined as weaker health returns of education, employment, and income for marginalized people, particularly Black individuals, than the returns for White people [5,6]. MDRs framework argues that systemic racism, social stratification, and other sources of inequalities, intentionally or unintentionally provides an unjust condition for Black and Brown people, while the same processes maintain the relatively higher status of privileged White people in the society. According to the MDRs, White privilege comes with the cost of minoritized and marginalized groups. As a result, even when the non-White groups climb up the social ladder, their health status is not great because the process of social mobility is far more taxing for them, and the real live consequences of SES and mobility are not comparable between non-White and White people. In the US society, White privilege is maintained by “Whites’ written laws, regulation, rules, norms, and standards”.

In this view, MDRs framework has provided a paradigm shift for studying health disparities that are not due to poverty but glitches in the system and social processes such as systemic racism that contribute to health inequalities. Unlike most of the research on health disparities that has traditionally - focused on the role of poverty and low SES as the mechanism for racial health inequalities, MDRs seek to understand how economic and health effects of available SES indicators vary across Whites and racial/ethnic minorities. In addition, MDRs explore racial/ethnic disparities across the full SES spectrum and allow SES returns to vary by race/ethnicity. An assumption that SES is similarly protective for all social groups is naïve and not supported by the evidence. In addition, MDRs explain why racial/ethnic health gap may widen, rather than narrow, as SES increases [5,6]. This framework provides a new explanation for why Black-White economic and health gaps extend to educated and employed (middle-class) Black communities [17,18].

Although not always called MDRs, weaker health effects of SES indicators such as education, income, and employment among Black than White individuals are reported by Williams, Hudson [19-21], Fuller-Rowel [22-25], Kaufman [26], Shapiro [27,28], Williams [29,30], Ceci [31], Ferarro [32], Navarro [33-35], Assari [5,6], and Thorpe [36-38]. These findings can be referred to as MDRs [5,6] a systemic phenomenon that is related to marginalization and holds for various SES indicators and health outcomes. The MDRs framework attributes worse-than-expected health of middle-class people of color not to poverty but the diminished effects of education, income, and employment in the lives of middle-class people of color. This phenomenon has recently attracted attention and has provided a novel approach to research on health disparities [39,40].

Extensive empirical evidence has supported the existence of MDRs and the contribution of such MDRs to racial and ethnic health disparities in the US. Previous work shows that due to MDRs, highly educated, employed, and high income Black people show worse mental [41], behavioral [42,43], and physical health [17], and unmet healthcare needs [44,45]. These patterns are non-specific and can be seen for mental health [46,47], chronic diseases [48-50], substance use [43,51,52], and mortality [53,54]. Recent studies have also shown that due to MDRs, diet [55], exercise [56], obesity [57,58] are also worse for Black middle-class. A recent study used the National Health and Nutrition Examination Survey (NHANES) data and showed that highly educated White people have low risk of cardiometabolic conditions, while highly educated, employed, and high-income Black people have a higher risk of cardiometabolic conditions. While the results varied for various conditions, obesity was not included in the study [59].

While MDRs are well-described, most of the MDRs literature on obesity as an outcome is focused on children and youth rather than adults [57,60,61]. As social determinants of obesity differ in age groups, there is a need to test the same MDRs for obesity in adults. In addition, most of the MDRs literature has used both genders. However, social determinants of obesity may vary between men and women. Thus, there is a need to test whether these MDRs hold for women as well.

To expand the literature, we conducted a secondary analysis of individual-level data from National Health and Nutrition Examination Survey (NHANES) with the following specific aims: Aim 1 was to determine the associations between educational attainment, employment, income, and obesity, and Aim 2 was to test diminished returns of education, employment, and income for Black women over the returns for White women at reproductive age. We focused on obesity in women at reproductive age because this outcome is a risk to the health of newborn and the mother [62]. Our first hypothesis was that education, income, and employment are inversely associated with odds of obesity, and our second hypothesis was that the inverse associations between education, income, and employment with the odds of obesity on health are weaker for Black than White women.

Methods

This cross-sectional study used the National Health and Nutrition Examination Survey (NHANES) data between 1999-2016 [63]. The NHANES is a state-of the art cross-sectional survey that provides nationally representative health estimates for the US population. The NHANES 1999-2016 response rate was 73.2% [64,65]. For this analysis, we included 5237 women at their reproductive age. All women were between 20 and 44 years of age. All participants were non-Hispanic Black or non-Hispanic White.

Outcome variable

We used obesity as the outcome. We used a dummy variable for obesity coded 1 if the body mass index (BMI) was equal or larger than 30.0 [66]. The NHANES has measured height and weight to calculate the BMI.

Main independent variables

The main independent variables of interest were education level, employment, and marital status. Educational attainment was a categorical variable with the following categories: 1) less than high school graduate, 2) high school graduate, or general equivalency diploma (GED), 3) some college, and 4) college degree. Employment was a dummy variable (=1, If individual 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). Household income was a three level variable: $0-$34,999, 35,000-$74,999 and ≥75,000.

Covariates

For demographic variables, we included age (years), sex, and marital status (1 = married, 0 = otherwise). We did not control for health behaviors such as smoking (never smoked, a former smoker and current smoker), drinking (never drink, former drinker and current drinker), and physical activity (vigorous activity) because they may explain racial variation in the link between SES and obesity.

Race

Moderator was race/ethnicity 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. The prevalence of obesity was greater than 10%: used weighted modified GLM (sub pop) [67-69] to produce prevalence ratios (PR) and the corresponding 95% confidence intervals (CI) [67,68]. We ran nested models with various combination of SES Indicators such as education, employment, and income. All models controlled for our interaction effects. Our models were performed without and with interaction terms between race and education, income, and employment. Finally, we stratified the analyses by race. All analyses were weighted using the NHANES individual-level sampling weights for 1999-2016 (8 waves of data) that makes the effect sizes and estimates representative of the national level for the US non-institutionalized population [70]. A P-value <0.05 was statistically significant (two-sided). We used STATA statistical software version 15 to perform all analyses.

Results

Table 1 shows the descriptive data of our participants. As this table shows, 5237 participants entered our analysis. From this number, 2023 were obese and 3214 were not obese. Average age of our participants was 32 years and 60% of them were married. From all our participants, 18% WERE Black and 82% were White, however, between 13 to 27% of White and Black women were obese.