How cumulative risks warrant a shift in our approach to racial health disparities: the case of lead, stress, and hypertension

Evaluating Race in Air Pollution and Health Research: Race, PM2.5 Air Pollution Exposure, and Mortality as a Case Study

PURPOSE OF REVIEW

Racial inequities in air pollution exposure have been documented. There is also interest in documenting the modifying role of race in the link between air pollution and health. However, the empirical literature in this area has yielded mixed results with potentially unclear policy implications. We critically evaluate recent empirical papers on the interactive association between race and air pollution exposure on adult mortality in the USA as a case study of the race, pollution, and health literature. Specifically, we evaluate these studies for the conceptualization and discussion of race and the use of race variables that may contribute to the ambiguous results and policy implications both in this specific literature and in the broader literature.

RECENT FINDINGS

We evaluate ten empirical studies from 2016 to 2022 on the modifying role of race in the association between short- and long-term PM2.5 exposure and specific types of adult mortality (all cause, non-accidental, and heart or cardiovascular diseases) in the USA. In addition to comparing and contrasting the empirical results, we focus our review on the conceptualization, measurement, modeling, and discussion of race and the race variables. Overall, the results indicate no consistent role of race in the association between PM2.5 exposure and mortality. Moreover, conceptualization and discussion of race was often brief and incomplete, even when the empirical results were unexpected or counterintuitive. To build on recent discussions in the epidemiology and environmental epidemiology literature more specifically, we provide a detailed discussion of the meaning of race, the race variables, and the cultural and structural racism that some argue are proxied by race variables. We use theoretical scholarship from the humanities and social sciences along with empirical work from the environmental literature to provide recommendations for future research that can provide an evidence base to inform both social and environmental policy.

Long-term effects of ambient PM2.5 on hypertension in multi-ethnic population from Sichuan province, China: a study based on 2013 and 2018 health service surveys

Hypertension, a major risk factor of many severe chronic diseases and leading cause of global disease burden, is reported to be associated with long-term exposure to PM_2.5. China's high PM_2.5 pollution level has become a major public health issue. However, existing studies from China have got inconsistent results with very limited investigation into the multi-ethnic peoples. This study adds multi-ethnic evidence from Sichuan Province, southwestern China, and assesses ethnic differences of PM_2.5 exposure effect on hypertension. We pooled large cross-sectional data from two surveys conducted in 2013 and 2018 to examine the association of long-term exposure to PM_2.5 on prevalence of hypertension in adults aged 30 years old and above. Community-specified annual PM_2.5 concentration was estimated using satellite data. Thirty-one thousand four hundred sixty-two participants with average exposure concentration of 32.8 μg/m³ were included. The proportions of the Han, the Tibetan, the Yi, and other ethnic people were 89.2%, 7.3%, 3.2%, and 0.3%, respectively. The adjusted odds ratio (OR) was 1.08 (95% CI, 1.04-1.12) for a 10 μg/m³ PM_2.5 concentration increment. The adjusted ORs for the Han, the Tibetan, and the Yi were 1.08 (95% CI, 1.04-1.12), 0.03 (95% CI, 0.00-0.27), and 1.75 (95% CI, 1.28-2.38) for a 10 μg/m³ PM_2.5 concentration increment, respectively. Stratification analysis found stronger associations in participants with chronic diseases and Yi minority population. The results showed that long-term exposure to PM_2.5 may increase the risk of hypertension prevalence in Chinese multi-ethnic adults. The associations were different among ethnicities.

Understanding the Link between Neighborhoods and Kidney Disease

Neighborhoods are where we live, learn, work, pray, and play. Growing evidence indicates that neighborhoods are an important determinant of health. The built features of our neighborhoods, such as the ways in which the streets are designed and connected and the availability of green spaces and transit stops, as well as the social features, such as the trust among neighbors and the perceptions of safety, may influence health through multiple pathways, such as access to important resources, psychosocial stress, and health behaviors. In particular, the extant literature consistently documents an association between neighborhood features and renal-associated conditions, such as cardiovascular disease, hypertension, diabetes, and obesity. There is also some evidence suggesting an association between neighborhood poverty and ESKD. The link between neighborhood and earlier stages of CKD, however, has been less clear, with most studies documenting no association. It may be that the neighborhood measures used in previous studies do not capture features of the neighborhood important for earlier stages of disease development and progression. It may also be that our current biomarkers (e.g., eGFR) and urine protein are not able to pick up very early forms of renal damage because of the kidney's overall high reserve capacity. This paper critically reviews the state of the literature on neighborhood and renal disease, with recommendations for neighborhood measures in future research. Neighborhoods are designed, built, and informed by policy, and thus, they are amenable to intervention, making them a potentially powerful way to improve renal health and reduce health inequalities at the population level.

Structural Characteristics of Tree Cover and the Association with Cardiovascular and Respiratory Health in Tampa, FL

Urban tree cover can provide several ecological and public health benefits. Secondary datasets for Tampa, FL, including sociodemographic variables (e.g., race/ethnicity), health data, and interpolated values for features of tree cover (e.g., percent canopy and leaf area index) were analyzed using correlation and regression. Percent canopy cover and leaf area index were inversely correlated to respiratory and cardiovascular outcomes, yet only leaf area index displayed a significant association with respiratory conditions in the logistic regression model. Percent racial/ethnic minority residents at the block group level was significantly negatively correlated with median income and tree density. Leaf area index was also significantly lower in block groups with more African-American residents. The percentage of African Americans (p = 0.101) and Hispanics (p < 0.001) were positively associated with respiratory outcomes while population density (p < 0.001), percent canopy (p < 0.01), and leaf area index (p < 0.01) were negatively associated. In multivariate models, higher tree density, leaf area index, and median income were significantly negatively associated with respiratory cases. Block groups with a higher proportion of African Americans had a higher odds of displaying respiratory admissions above the median rate. Tree density and median income were also negatively associated with cardiovascular cases. Home ownership and tree condition were significantly positively associated with cardiovascular cases.

Housing as a Platform for Health and Equity: Evidence and Future Directions

The links between housing and health are now known to be strong and multifaceted and to generally span across 4 key pillars: stability, affordability, quality and safety, and neighborhood opportunity. Housing disparities in the United States are tenaciously patterned along axes of social inequality and contribute to the burden related to persistently adverse health outcomes in affected groups. Appreciating the multidimensional relationship between housing and health is critical in moving the housing and health agenda forward to inspire greater equity.We assessed the current state of research on housing and health disparities, and we share recommendations for achieving opportunities for health equity centered on a comprehensive framing of housing.Despite the vastness of existing research, we must contextualize the housing and health disparities nexus in a broader web of interrelated variables emerging from the same roots of structural inequalities. There is more we can do to maximize the extent to which existing research furthers our understanding of housing's relationship to health and potential related interventions; however, there are also several areas where new research is warranted.

Towards environmental health equity in health impact assessment: innovations and opportunities

OBJECTIVES

As global environmental change drives inequitable health outcomes, novel health equity assessment methodologies are increasingly required. We review literatures on equity-focused HIA to clarify how equity is informing HIA practice, and to surface innovations for assessing health equity in relation to a range of exposures across geographic and temporal scales.

METHODS

A narrative review of the health equity and HIA literatures analysed English articles published between 2003 and 2017 across PubMed, PubMed Central, Biomed Central and Ovid Medline. Title and abstract reviews of 849 search results yielded 89 articles receiving full text review.

RESULTS

Considerations of equity in HIA increased over the last 5 years, but equity continues to be conflated with health disparities rather than their root causes (i.e. inequities). Lessons from six literatures to inform future HIA practice are described: HIA for healthy cities, climate change vulnerability assessment, cumulative health risk assessment, intersectionality-based policy analysis, corporate health impact assessment and global health impact assessment.

CONCLUSIONS

Academic reporting on incorporating equity in HIA practice has been limited. Nonetheless, significant methodological advancements are being made to examine the health equity implications of multiple environmental exposures.

A Tale of Two Patients: Patient-Centered Approaches to Adherence as a Gateway to Reducing Disparities

The disparate effects of social determinants of health on cardiovascular health status and health care have been extensively documented by epidemiology. Yet, very little attention has been paid to how understanding and addressing social determinants of health might improve the quality of clinical interactions, especially by improving patients' adherence to recommended therapies. We present a case and suggested approach to illustrate how cardiovascular clinicians can use patient-centered approaches to identify and address social determinants of health barriers to adherence and reduce the impact of unconscious clinician biases. We propose that cardiovascular clinicians (1) recognize that patients may have different belief systems about illnesses' cause and treatment, which may influence their actions, and not assume they share one's experiences or explanatory model; (2) Endeavor to understand the individual patient before you; (3) based on that understanding, tailor your approach to that individual. We suggest a previously-developed mnemonic for an approach to RESPECT the patient: First, show Respect; then elicit patients' understandings of their illness by asking about their Explanatory model. Ask about the patient's Social context, share Power in the interaction, show Empathy, ask about Concerns or fears, and work to develop Trust by building the relationship over time. We provide additional clinical resources to support these efforts, including lay descriptions of cardiovascular conditions, challenges to adherence, and suggested strategies to address them.

Air Pollution, Cardiovascular Outcomes, and Social Disadvantage: The Multi-ethnic Study of Atherosclerosis

BACKGROUND

Social factors may enhance health effects of air pollution, yet empirical support is inconsistent. The interaction of social and environmental factors may only be evident with long-term exposures and outcomes that reflect long-term disease development.

METHODS

We used cardiac magnetic resonance imaging data from the Multi-Ethnic Study of Atherosclerosis to assess left-ventricular mass index (LVMI) and left-ventricular ejection fraction (LVEF). We assigned residential concentrations of fine particulate matter (PM2.5), oxides of nitrogen, and nitrogen dioxide in the year 2000 to each participant in 2000 using prediction models. We examined modifying roles of four measures of adversity: race/ethnicity, racial/ethnic residential segregation, and socioeconomic status and psychosocial adversity as composite indices on the association between air pollution and LVMI or LVEF.

RESULTS

Compared with whites, blacks showed a stronger adjusted association between air pollution and LVMI. For example, for each 5 µg/m greater PM2.5 level, whites showed a 1.0 g/m greater LVMI (95% confidence interval = -1.3, 3.1), while blacks showed an additional 4.0 g/m greater LVMI (95% confidence interval = 0.3, 8.2). Results were similar for oxides of nitrogen and nitrogen dioxide with regard to black race and LVMI. However, we found no evidence of a modifying role of other social factors or ethnic groups. Furthermore, we found no evidence of a modifying role for any social factors or racial/ethnic groups on the association between air pollution and LVEF.

CONCLUSIONS

Our results suggest that racial group membership may modify the association between air pollution and cardiovascular disease.

The current state of ethnic and racial disparities in cardiovascular care: lessons from the past and opportunities for the future

Significant racial/ethnic disparities have been documented in cardiovascular care. Although health care quality is improving for many Americans, differences in clinical outcomes have persisted between racial/ethnic minority patients and non-minorities, even when income, education level, and site of care are taken into consideration. Potential causes of disparities are complex and are related to differences in risk factor prevalence and control, use of evidence-based procedures and medications, and social and environmental factors. Minority patients are more likely to receive care from lower-quality health care providers and institutions and experience more barriers to accessing care. Factors such as stereotyping and bias in medicine are hard to quantify, but likely contribute to differences in treatment. Recent trends suggest that some disparities are decreasing. Opportunities for change and improvement exist for patients, providers, and health care systems. Promising interventions, such as health policy changes, quality improvement programs, and culturally targeted community and clinic-based interventions offer hope that high-quality health care in the USA can be provided to all patients.

The public health exposome: a population-based, exposure science approach to health disparities research

The lack of progress in reducing health disparities suggests that new approaches are needed if we are to achieve meaningful, equitable, and lasting reductions. Current scientific paradigms do not adequately capture the complexity of the relationships between environment, personal health and population level disparities. The public health exposome is presented as a universal exposure tracking framework for integrating complex relationships between exogenous and endogenous exposures across the lifespan from conception to death. It uses a social-ecological framework that builds on the exposome paradigm for conceptualizing how exogenous exposures "get under the skin". The public health exposome approach has led our team to develop a taxonomy and bioinformatics infrastructure to integrate health outcomes data with thousands of sources of exogenous exposure, organized in four broad domains: natural, built, social, and policy environments. With the input of a transdisciplinary team, we have borrowed and applied the methods, tools and terms from various disciplines to measure the effects of environmental exposures on personal and population health outcomes and disparities, many of which may not manifest until many years later. As is customary with a paradigm shift, this approach has far reaching implications for research methods and design, analytics, community engagement strategies, and research training.

When identifying health disparities as a problem is a problem: pedagogical strategies for examining racialized contexts

The current study presents a critical discussion on community responses to health disparity research and the need for utilizing pedagogical strategies to prepare students to understand and address health disparities in racialized contexts. Qualitative research methods were used to examine community responses to media stories on two health disparity research projects, and four themes emerged: naming health disparities is a tool for dividing, structural racism does not exist, naming of health disparities is a political act, and health disparities exist because of individual-level deficiencies. The implications for teaching students about racial health disparities are presented and discussed.

Perceived racial discrimination and hypertension: a comprehensive systematic review

OBJECTIVE

Discrimination is posited to underlie racial disparities in hypertension. Extant literature suggests a possible association between racial discrimination and blood pressure, although inconsistent findings have been reported. The aim of this comprehensive systematic review was to quantitatively evaluate the association between perceived racial discrimination with hypertensive status and systolic, diastolic, and ambulatory blood pressure.

METHOD

Electronic database search of PubMed and PsycINFO (keywords: blood pressure/hypertension/diastolic/systolic, racism/discrimination/prejudice/unfair treatment) was combined with descendancy and ascendancy approaches. Forty-four articles (N = 32,651) met inclusion criteria. Articles were coded for demographics, hypertensive diagnosis, blood pressure measurement, discrimination measure and constructs, study quality, and effect sizes.

RESULTS

Random effects meta-analytic models were tested based on Fisher's Z, the derived common effect size metric. Overall, perceived racial discrimination was associated with hypertensive status, Zhypertension = 0.048, 95% CI [.013, .087], but not with resting blood pressure, Zsystolic = 0.011, 95% CI [-.006, .031], Zdiastolic = .016, 95% CI [-.006, .034]. Moderators that strengthened the relation included sex (male), race (Black), age (older), education (lower), and hypertensive status. Perceived discrimination was most strongly associated with nighttime ambulatory blood pressure, especially among Blacks.

CONCLUSIONS

Despite methodological limitations in the existing literature, there was a small, significant association between perceived discrimination and hypertension. Future studies should consider ambulatory nighttime blood pressure, which may more accurately capture daily variation attributable to experienced racial discrimination. Perceived discrimination may partly explain racial health disparities.

Do psychosocial stress and social disadvantage modify the association between air pollution and blood pressure?: the multi-ethnic study of atherosclerosis

Researchers have theorized that social and psychosocial factors increase vulnerability to the deleterious health effects of environmental hazards. We used baseline examination data (2000-2002) from the Multi-Ethnic Study of Atherosclerosis. Participants were 45-84 years of age and free of clinical cardiovascular disease at enrollment (n = 6814). The modifying role of social and psychosocial factors on the association between exposure to air pollution comprising particulate matter less than 2.5 µm in aerodynamic diameter (PM2.5) and blood pressure measures were examined using linear regression models. There was no evidence of synergistic effects of higher PM2.5 and adverse social/psychosocial factors on blood pressure. In contrast, there was weak evidence of stronger associations of PM2.5 with blood pressure in higher socioeconomic status groups. For example, those in the 10th percentile of the income distribution (i.e., low income) showed no association between PM2.5 and diastolic blood pressure (b = -0.41 mmHg; 95% confidence interval: -1.40, 0.61), whereas those in the 90th percentile of the income distribution (i.e., high income) showed a 1.52-mmHg increase in diastolic blood pressure for each 10-µg/m(3) increase in PM2.5 (95% confidence interval: 0.22, 2.83). Our results are not consistent with the hypothesis that there are stronger associations between PM2.5 exposures and blood pressure in persons of lower socioeconomic status or those with greater psychosocial adversity.

"Every shut eye, ain't sleep": The role of racism-related vigilance in racial/ethnic disparities in sleep difficulty

Although racial/ethnic disparities in health have been well-characterized in biomedical, public health, and social science research, the determinants of these disparities are still not well-understood. Chronic psychosocial stress related specifically to the American experience of institutional and interpersonal racial discrimination may be an important determinant of these disparities, as a growing literature in separate scientific disciplines documents the adverse health effects of stress and the greater levels of stress experienced by non-White compared to White Americans. However, the empirical literature on the importance of stress for health and health disparities specifically due to racial discrimination, using population-representative data, is still small and mixed. In this paper, we explore the association between a novel measure of racially-salient chronic stress - "racism-related vigilance" - and sleep difficulty. We found that, compared to the White adults in our sample, Black (but not Hispanic) adults reported greater levels of vigilance. This vigilance was positively associated with sleep difficulty to similar degrees for all racial/ethnic groups in our sample (White, Black, Hispanic). Black adults reported greater levels of sleep difficulty compared to White adults. This disparity was slightly attenuated after adjustment for education and income. However, this disparity was completely attenuated after adjustment for racism-related vigilance. We found similar patterns of results for Hispanic compared to White adults, however, the disparities in sleep difficulty were smaller and not statistically significant. Because of the importance of sleep quality to health, our results suggest that the anticipation of and perseveration about racial discrimination is an important determinant of racial disparities in health.

Black-white blood pressure disparities: depressive symptoms and differential vulnerability to blood lead

BACKGROUND

Blacks have higher hypertension rates than whites, but the reasons for these disparities are unknown. Differential vulnerability, through which stress alters vulnerability to the effects of environmental hazards, is an emergent notion in environmental health that may contribute to these disparities.

OBJECTIVES

We examined whether blacks and whites exhibit different associations between blood lead (BPb) and blood pressure (BP) and whether depressive symptoms may play a role.

METHODS

Using the National Health and Nutrition Examination Survey 2005-2008, we regressed BP on the three-way interaction among race/ethnicity, BPb, and depressive symptoms in blacks and whites ≥ 20 years of age.

RESULTS

Blacks but not whites showed a positive association between BPb and systolic blood pressure (SBP). The disparity in this association between blacks and whites appeared to be specific to the high depressive symptoms group. In the low depressive symptoms group, there was no significant black-white disparity (βinteraction = 0.9 mmHg; 95% CI: -0.9, 2.7). However, of those with high depressive symptoms, blacks and whites had 5.6 mmHg (95% CI: 2.0, 9.2) and 1.2 mmHg (95% CI: -0.5, 2.9) increases in SBP, respectively, in association with each doubling of BPb (βinteraction = 4.4 mmHg; 95% CI: 0.5, 8.3). The pattern of results was similar for diastolic blood pressure.

CONCLUSIONS

Our results suggest that depressive symptoms may contribute to the black-white disparity in the association between BPb and BP. Depressive symptoms may result, in part, from psychosocial stress. Our results support the notion that stress increases vulnerability to the health effects of environmental hazards and suggest that stress-related vulnerability may be an important determinant of racial/ethnic health disparities.

A novel look at racial health disparities: the interaction between social disadvantage and environmental health

OBJECTIVES

We explored the notion that social disadvantage increases vulnerability to the health effects of environmental hazards. Specifically, we examined (1) whether race modifies the association between blood lead and blood pressure and (2) whether socioeconomic status (SES) plays a role in this modifying effect.

METHODS

Using the National Health and Nutrition Examination Survey (2001-2008) and linear regression, we estimated the association between blood lead and blood pressure. Using interactions among race, SES, and lead, we estimated this association by levels of social disadvantage.

RESULTS

Black men and women showed a 2.8 (P < .001) and 4.0 (P < .001) millimeters mercury increase in SBP, respectively, for each doubling of blood lead. White adults showed no association. This lead-SBP association exhibited by Blacks was primarily isolated to Blacks of low SES. For example, poor but not nonpoor Black men showed a 4.8 millimeters mercury (P < .001) increase in SBP for each doubling of blood lead.

CONCLUSIONS

Our results suggest that social disadvantage exacerbates the deleterious health effects of lead. Our work provides evidence that social and environmental factors must be addressed together to eliminate health disparities.

Theory-guided selection of discrimination measures for racial/ ethnic health disparities research among older adults

OBJECTIVE

Discrimination may contribute to health disparities among older adults. Existing measures of perceived discrimination have provided important insights but may have limitations when used in studies of older adults. This article illustrates the process of assessing the appropriateness of existing measures for theory-based research on perceived discrimination and health.

METHOD

First, we describe three theoretical frameworks that are relevant to the study of perceived discrimination and health-stress-process models, life course models, and the Public Health Critical Race (PHCR) praxis. We then review four widely-used measures of discrimination, comparing their content and describing how well they address key aspects of each framework, and discussing potential areas of modification.

DISCUSSION

Using theory to guide measure selection can help improve understanding of how perceived discrimination may contribute to racial/ethnic health disparities among older adults.