Dietary Potential Renal Acid Load and Risk of Albuminuria and Reduced Kidney Function in the Jackson Heart Study.

OBJECTIVE: Diets high in sulfur-rich protein and low in fruit and vegetables affect human acid-base balance adversely and may have a harmful effect on progression of chronic kidney disease (CKD). Little is known about the relationship of participant characteristics, dietary acid load (DAL), and kidney injury in African-Americans with high risk of CKD progression. DESIGN AND METHODS: We examined the association of DAL with CKD in 3,257 African-Americans aged >20 years in Jackson Heart Study. DAL was measured with nutrient intakes assessed with a food frequency questionnaire, using a model described by Remer and Manz. We tested associations of participant characteristics with DAL using median regression, and associations of DAL with albuminuria (>17 mg/g for men, >25 mg/g for women), reduced kidney function (eGFR <60 mL/minute/1.73 m2), or CKD defined as albuminuria or reduced kidney function using logistic regression. We further explored whether endothelin and aldosterone production in participants with hypertension mediated risk of albuminuria or reduced kidney function due to the intake of an acid-inducing diet. RESULTS: Younger adults, men, and those with higher body mass index had higher DAL. Higher DAL, compared with lower, was associated with greater odds of reduced kidney function (OR [95% CI]: 2.82 [1.40-4.75]). Higher DAL was also associated with greater risk of CKD, and this persisted after adjustment for confounders. Results were similar in adults with hypertension; the OR [95% CI] for highest, versus lowest, tertile of DAL with albuminuria was 1.66 [1.01-2.59]. Aldosterone and endothelin mediated the association between DAL and albuminuria; the OR [95% CI] in the highest tertile was no longer significant 1.53 [0.97-2.40] after their inclusion. CONCLUSIONS: Higher DAL was associated with higher prevalence of CKD and with reduced kidney function. DAL may be an important target for future interventions in African-Americans at high risk of CKD.

Residential Proximity to Traffic-Related Pollution and Atherosclerosis in 4 Vascular Beds Among African-American Adults: Results From the Jackson Heart Study.

To our knowledge, no study has investigated the association of long-term exposure to traffic pollution with markers of atherosclerosis in 4 vascular beds simultaneously in an all-African-American cohort. Among participants in the Jackson Heart Study (Jackson, Mississippi; baseline mean age = 55.5 (standard deviation, 12.7) years), we used linear regression to estimate percent differences in carotid intima-media thickness (CIMT) at baseline (2004) and used modified Poisson regression (robust error variance) to estimate prevalence ratios for peripheral artery disease (PAD), coronary artery calcification (CAC), and abdominal aortic calcification (AAC) at the first follow-up visit (2005-2008) for persons living less than 150 m (versus more than 300 m) from major roadways, adjusting for confounders. Living less than 150 m from such roadways was associated with a significant 6.67% (95% confidence interval: 1.28, 12.35) increase in CIMT (4,800 participants). PAD prevalence among persons living less than 150 m from a major roadway was 1.17 (95% confidence interval: 0.73, 1.86) times that of persons living more than 300 m away (4,443 participants), but this result was not statistically significant. There was no association for CAC or AAC. The association with CIMT was stronger in participants with a cardiovascular disease history than in those without one (P = 0.04). We observed an association in the carotid vascular beds but not the coronary, abdominal, or peripheral vascular beds. Our results highlight the need to consider residential proximity to roadways as a potential cardiovascular disease risk factor for blacks.

The impact of neighborhood on physical activity in the Jackson Heart Study.

Physical inactivity is an independent risk factor for many diseases. Most research has focused on individual-level factors for physical activity (PA), but evidence suggests that neighborhood is also important. We examined baseline data collected between 2000 and 2004 from 5236 participants in the Jackson Heart Study to determine the effects of neighborhood on 2 types of PA: Active Living (AL), and Sports and Exercise (Sport) in an all-African American cohort. Participants were georeferenced and data from individual baseline questionnaires and US Census were analyzed using descriptive, bivariate, and multilevel models. In both types of PA, neighborhood factors had an independent and additive effect on AL and Sport. Living in an urban (p=0.003) or neighborhood with a higher percentage of residents with less than a high school education (p<0.001) was inversely associated with AL. There was an inverse interaction effect between individual and lower neighborhood education (p=0.01), as well as between age and urban neighborhoods (p=0.02) on AL. Individual level education (OR=1.30) and per capita income (OR=1.07) increased the odds of moderate-to-high sports. Future studies should focus on what contextual aspects of urban or less educated neighborhoods are influential in determining PA, as well as longitudinal multilevel analyses of neighborhood effects on PA.

Using Community Feedback to Improve Community Interventions: Results From the Deep South Network for Cancer Control Project.

The Deep South Network for Cancer Control (DSNCC), initiated in 2000, is a dual-state, community-based participatory research infrastructure composed of academic and community partners committed to reducing cancer disparities among underserved African Americans in 12 designated counties of the Alabama Black Belt and the Mississippi Delta, 2 historically underserved areas of the country. Local residents trained as Community Health Advisors as Research Partners implemented a 3-tier community action plan (CAP) focused on promoting cancer screening, physical activity, and nutrition. Breast, cervical and colorectal cancer screening, healthy eating habits, and physical activity levels increased among many, but not all, African American women in the 12-county DSNCC coverage area. Seeking to improve our reach to include participants who reported they had never heard of the DSNCC or participated in the CAP, we conducted in-depth conversations with community residents about reasons for selective nonparticipation and ways to improve participation in the DSNCC community health interventions. Three patterns and their associated themes described ways to improve the penetration of CAP strategies and tailor them to effectively reach underserved African Americans in the intervention counties. We conclude with lessons learned for future interventions.

Genome-wide association study for serum urate concentrations and gout among African Americans identifies genomic risk loci and a novel URAT1 loss-of-function allele.

Serum urate concentrations are highly heritable and elevated serum urate is a key risk factor for gout. Genome-wide association studies (GWAS) of serum urate in African American (AA) populations are lacking. We conducted a meta-analysis of GWAS of serum urate levels and gout among 5820 AA and a large candidate gene study among 6890 AA and 21 708 participants of European ancestry (EA) within the Candidate Gene Association Resource Consortium. Findings were tested for replication among 1996 independent AA individuals, and evaluated for their association among 28 283 EA participants of the CHARGE Consortium. Functional studies were conducted using (14)C-urate transport assays in mammalian Chinese hamster ovary cells. In the discovery GWAS of serum urate, three loci achieved genome-wide significance (P< 5.0 × 10(-8)): a novel locus near SGK1/SLC2A12 on chromosome 6 (rs9321453, P= 1.0 × 10(-9)), and two loci previously identified in EA participants, SLC2A9 (P= 3.8 × 10(-32)) and SLC22A12 (P= 2.1 × 10(-10)). A novel rare non-synonymous variant of large effect size in SLC22A12, rs12800450 (minor allele frequency 0.01, G65W), was identified and replicated (beta -1.19 mg/dl, P= 2.7 × 10(-16)). (14)C-urate transport assays showed reduced urate transport for the G65W URAT1 mutant. Finally, in analyses of 11 loci previously associated with serum urate in EA individuals, 10 of 11 lead single-nucleotide polymorphisms showed direction-consistent association with urate among AA. In summary, we identified and replicated one novel locus in association with serum urate levels and experimentally characterize the novel G65W variant in URAT1 as a functional allele. Our data support the importance of multi-ethnic GWAS in the identification of novel risk loci as well as functional variants.

Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study.

The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10(-8)) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10(-8)). The top IBC association for SBP was rs2012318 (P= 6.4 × 10(-6)) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10(-6)) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity.

Perceived discrimination and hypertension among African Americans in the Jackson Heart Study.

OBJECTIVES: Using Jackson Heart Study data, we examined whether perceived discrimination was associated with prevalent hypertension in African Americans. METHODS: Everyday discrimination, lifetime discrimination, burden of discrimination, and stress from discrimination were examined among 4939 participants aged 35 to 84 years (women = 3123; men = 1816). We estimated prevalence ratios of hypertension by discrimination, and adjusted for age, gender, socioeconomic status, and risk factors. RESULTS: The prevalence of hypertension was 64.0% in women and 59.7% in men. After adjustment for age, gender, and socioeconomic status, lifetime discrimination and burden of discrimination were associated with greater hypertension prevalence (prevalence ratios for highest vs lowest quartile were 1.08 [95% confidence interval (CI) = 1.02, 1.15] and 1.09 [95% CI = 1.02,1.16] for lifetime discrimination and burden of discrimination, respectively). Associations were slightly weakened after adjustment for body mass index and behavioral factors. No associations were observed for everyday discrimination. CONCLUSIONS: Further understanding the role of perceived discrimination in the etiology of hypertension may be beneficial in eliminating hypertension disparities.

Social patterning of cumulative biological risk by education and income among African Americans.

OBJECTIVES: We examined the social patterning of cumulative dysregulation of multiple systems, or allostatic load, among African Americans adults. METHODS: We examined the cross-sectional associations of socioeconomic status (SES) with summary indices of allostatic load and neuroendocrine, metabolic, autonomic, and immune function components in 4048 Jackson Heart Study participants. RESULTS: Lower education and income were associated with higher allostatic load scores in African American adults. Patterns were most consistent for the metabolic and immune dimensions, less consistent for the autonomic dimension, and absent for the neuroendocrine dimension among African American women. Associations of SES with the global allostatic load score and the metabolic and immune domains persisted after adjustment for behavioral factors and were stronger for income than for education. There was some evidence that the neuroendocrine dimension was inversely associated with SES after behavioral adjustment in men, but the immune and autonomic components did not show clear dose-response trends, and we observed no associations for the metabolic component. CONCLUSIONS: Findings support our hypothesis that allostatic load is socially patterned in African American women, but this pattern is less consistent in African American men.

Are religiosity and spirituality associated with obesity among African Americans in the Southeastern United States (the Jackson Heart Study)?

There are several lines of evidence that suggest religiosity and spirituality are protective factors for both physical and mental health, but the association with obesity is less clear. This study examined the associations between dimensions of religiosity and spirituality (religious attendance, daily spirituality, and private prayer), health behaviors and weight among African Americans in central Mississippi. Jackson Heart Study participants with complete data on religious attendance, private prayer, daily spirituality, caloric intake, physical activity, depression, and social support (n = 2,378) were included. Height, weight, and waist circumference were measured. We observed no significant association between religiosity, spirituality, and weight. The relationship between religiosity/spirituality and obesity was not moderated by demographic variables, psychosocial variables, or health behaviors. However, greater religiosity and spirituality were related to lower energy intake, less alcohol use, and less likelihood of lifetime smoking. Although religious participation and spirituality were not cross-sectionally related to weight among African Americans, religiosity and spirituality might promote certain health behaviors. The association between religion and spirituality and weight gain deserves further investigation in studies with a longitudinal study design.

Geographic representation of the jackson heart study cohort to the African-American population in Jackson, Mississippi.

Recent advances in geographic information systems software and multilevel methodology provide opportunities for more extensive characterization of "at-risk" populations in epidemiologic studies. The authors used age-restricted, geocoded data from the all-African-American Jackson Heart Study (JHS), 2000-2004, to demonstrate a novel use of the Lorenz curve and Gini coefficient to determine the representativeness of the JHS cohort to the African-American population in a geographic setting. The authors also used a spatial binomial model to assess the geographic variability in participant recruitment across the Jackson, Mississippi, Metropolitan Statistical Area. The overall Gini coefficient, an equality measure that ranges from 0 (perfect equality) to 1 (perfect inequality), was 0.37 (95% confidence interval (CI): 0.30, 0.45), indicating moderate representation. The population of sampled women (Gini coefficient = 0.34, 95% CI: 0.30, 0.39) tended to be more representative of the underlying population than did the population of sampled men (Gini coefficient = 0.49, 95% CI: 0.35, 0.61). Representative recruitment of JHS participants was observed in predominantly African-American and mixed-race census tracts and in the center of the study area, the area nearest the examination clinic. This is of critical importance as the authors continue to explore novel approaches to investigate the geographic variation in disease etiology.

Associations of fast food restaurant availability with dietary intake and weight among African Americans in the Jackson Heart Study, 2000-2004.

OBJECTIVES: We examined the associations of fast food restaurant (FFR) availability with dietary intake and weight among African Americans in the southeastern United States. METHODS: We investigated cross-sectional associations of FFR availability with dietary intake and body mass index (BMI) and waist circumference in 4740 African American Jackson Heart Study participants (55.2 ± 12.6 years, 63.3% women). We estimated FFR availability using circular buffers with differing radii centered at each participant's geocoded residential location. RESULTS: We observed no consistent associations between FFR availability and BMI or waist circumference. Greater FFR availability was associated with higher energy intake among men and women younger than 55 years, even after adjustment for individual socioeconomic status. For each standard deviation increase in 5-mile FFR availability, the energy intake increased by 138 kilocalories (confidence interval [CI] = 70.53, 204.75) for men and 58 kilocalories (CI = 8.55, 105.97) for women. We observed similar associations for the 2-mile FFR availability, especially in men. FFR availability was also unexpectedly positively associated with total fiber intake. CONCLUSIONS: FFR availability may contribute to greater energy intake in younger African Americans who are also more likely to consume fast food.

Psychometric testing of the daily spiritual experiences scale among African Americans in the Jackson Heart Study.

This study provided the first examination of the psychometric properties of the 6-item Daily Spiritual Experiences Scale (DSES) in a large African American sample, the Jackson Heart Study (JHS). The JHS included measures of spiritual (DSES) and religious practices. Internal reliability, dimensionality, fit indices, and correlation were assessed. DSES scores reflected frequent daily spiritual experiences (12.84 ± 4.72) and reliability scores were high (α = 0.85; 95% CI 0.84-0.86). The DSES loaded on a single factor, with significant goodness-of-fit scores (RMSEA = 0.094, P < 0.01). Moderate significant correlations were noted among DSES items. Our findings confirm that the 6-item DSES had excellent psychometric properties in this sample.

Association of socioeconomic status and CKD among African Americans: the Jackson Heart Study.

BACKGROUND: Socioeconomic status (SES) is recognized as a key social environmental factor because it has implications for access to resources that help individuals care for themselves and others. Few studies have examined the association of SES with chronic kidney disease (CKD) in high-risk populations. STUDY DESIGN: Single-site longitudinal population-based cohort. SETTING & PARTICIPANTS: Data for this study were drawn from the baseline examination of the Jackson Heart Study. The analytic cohort consisted of 3,430 African American men and women living in the tricounty region of the Jackson, MS, metropolitan area with complete data to determine CKD status. PREDICTOR: High SES (defined as having a family income at least 3.5 times the poverty level or having at least 1 undergraduate degree). OUTCOMES & MEASUREMENTS: CKD (defined as the presence of albuminuria or decreased estimated glomerular filtration rate [<60 mL/min/1.73 m(2)]). Associations were explored using bivariable analyses and multivariable logistic regression analyses adjusting for CKD and cardiovascular disease risk factors, as well as demographic factors. RESULTS: The prevalence of CKD in the Jackson Heart Study was 20% (865 of 3,430 participants). Proportions of the Jackson Heart Study cohort with albuminuria and decreased estimated glomerular filtration rate were 12.5% (429 of 3,430 participants) and 10.1% (347 of 3,430 participants), respectively. High SES was associated inversely with CKD. The odds of having CKD were 41% lower for affluent participants than their less affluent counterparts. There were no statistically significant interactions between sex and education or income, although subgroup analysis showed that high income was associated with CKD in men (OR, 0.47; 95% CI, 0.23-0.97), but not women (OR, 0.64; 95% CI, 0.40-1.03). LIMITATIONS: Models were estimated using cross-sectional data. CONCLUSION: CKD is associated with SES. Additional research is needed to elucidate the impact of wealth and social contexts in which individuals are embedded and the mediating effects of sociocultural factors.

Methods for retrospective geocoding in population studies: the Jackson Heart Study.

The increasing use of geographic information systems (GIS) in epidemiological population studies requires careful attention to the methods employed in accomplishing geocoding and creating a GIS. Studies have provided limited details,hampering the ability to assess validity of spatial data. The purpose of this paper is to describe the multiphase geocoding methods used to retrospectively create a GIS in the Jackson Heart Study (JHS). We used baseline data from 5,302 participants enrolled in the JHS between 2000 and 2004 in a multiphase process to accomplish geocoding2 years after participant enrollment. After initial deletion of ungeocodable addresses(n=52), 96% were geocoded using ArcGIS. An interactive method using data abstraction from participant records, use of additional maps and street reference files,and verification of existence of address, yielded successful geocoding of all but 13 addresses. Overall, nearly 99% (n=5,237) of the JHS cohort was geocoded retrospectively using the multiple strategies for improving and locating geocodable addresses. Geocoding validation procedures revealed highly accurate and reliable geographic data. Using the methods and protocol developed provided a reliable spatial database that can be used for further investigation of spatial epidemiology. Baseline results were used to describe participants by select geographic indicators, including residence in urban or rural areas, as well as to validate the effectiveness of the study's sampling plan. Further, our results indicate that retrospectively developing a reliable GIS for a large, epidemiological study is feasible. This paper describes some of the challenges in retrospectively creating a GIS and provides practical tips that enhanced the success.

Physical activity and obesity in African Americans: the Jackson Heart Study.

OBJECTIVES: To better understand how obesity and low levels of physical activity (PA) contribute to racial health disparities, we examined the association of PA domains (work, home life, and leisure) with indicators of socioeconomic status and markers of obesity in African Americans. METHODS: These cross sectional analyses of interview and clinical measures from the baseline visit of the Jackson Heart Study of cardiovascular disease (CVD) in African Americans of the Jackson, Mississippi metropolitan statistical area included 3,174 women and 1,830 men aged 21-95 years. The main measures were active living, sport, work, home life, and total PA scores; participation in regular moderate or vigorous intensity leisure physical activity (MVLPA); demographics, body mass index (BMI), waist circumference (WC) and CVD risk factors. RESULTS: The sample was 63% female, 81% high school or college graduates, with 51% aged 45-64 years, and mostly overweight (32%) or obese (53%). Women were less active than men in all domains except home life. Total PA was inversely associated with WC in women and men. The overweight (BMI 25-29.9) group was most active in all domains except work; active living and sport PA and prevalence of MVLPA then declined in a dose response association with increasing BMI. Work PA was associated with the lowest BMI but otherwise with indicators of less favorable socioeconomic status and health. CONCLUSIONS: Observed differences in PA in African Americans by domain and association with obesity biomarkers suggest areas for future study and intervention to reduce health disparities.

The role of community health advisors in community-based participatory research.

Mistrust and fear of research often exist in minority communities because of assumptions, preconceived ideas, and historical abuse and racism that continue to influence research participation. The research establishment is full of well-meaning 'outsider' investigators who recognize discrimination, health disparities, and insufficient health care providers in minority communities, but struggle in breaking through this history of mistrust. This article provides ethical insights from one such 'insider-outsider', community-based participatory research project implemented via community health advisors in the Mississippi Delta. Both community-based participatory research and community health advisors provide opportunities to address the ethical issues of trust, non-maleficence, and justice in minority communities. Implications for ethics-driven nursing research are discussed.

Race, stability of health insurance coverage, and prescription medication use.

OBJECTIVE: To determine the effects of health insurance and race on prescription medication use and expense. METHODS: An observational, non-experimental design was used. Multivariable regression analyses were conducted to evaluate the independent effects of health insurance status and race on prescription medication use and expense while controlling for sociodemographic, geographic, and health status characteristics. The sample consisted of 19,035 participants in the 1996 through 2003 Medical Expenditure Panel Survey. FINDINGS: European Americans spent about $300 to $400 more and used three to four more prescriptions annually compared to other racial groups. Prescription medication expenses increased as time spent uninsured increased. Participants with part-year coverage filled four fewer prescriptions than those with full-year health insurance coverage. Participants with private coverage spent less on prescription medications compared to those with public and those with dual public and private coverage ($1,194 vs. $1,931 and $2,076, respectively; p < or = 0.001). CONCLUSIONS: Significant racial and health insurance status disparities in prescription medication use and expenses exist after controlling for sociodemographic, geographic, and health status characteristics.

Life Course Socioeconomic Status and Hypertension in African American Adults: The Jackson Heart Study.

BACKGROUND: Limited research has examined the association of life-course socioeconomic status (SES) with hypertension prevalence and incidence in a large cohort of African Americans. METHODS: Among 4,761 participants from the Jackson Heart Study (JHS), we examined the association of SES indicators with prevalent and incident hypertension. We used multivariable Poisson regression to estimate prevalence ratios (PR, 95% confidence interval-CI) of baseline (2000-2004) hypertension by adult (education, income, occupation, wealth) and childhood (mother's education) SES. Cox proportional hazards regression was used to estimate hazard ratios (HR, 95% CI) of incident hypertension by adult and childhood SES (2005-2013; 7.21 median years of follow-up). We also examined the association of childhood-to-adult SES mobility (parent-to-adult education) with prevalent and incident hypertension. Model 1 adjusted for age and sex. Model 2 added waist circumference, behaviors (smoking, alcohol, physical activity, diet), and diabetes prevalence. RESULTS: High (vs. low) adult SES measures were associated with a lower prevalence of hypertension, with the exception of having a college degree and upper-middle income (PR: 1.04, 95% CI: 1.01, 1.07; PR: 1.05, 95% CI: 1.01, 1.09, respectively). Higher childhood SES was associated with a lower prevalence and risk of hypertension (PR: 0.83, 95%: CI 0.75, 0.91; HR: 0.76, 95% CI: 0.65, 0.89, respectively). Upward mobility and consistent high SES (vs. consistent low SES) from childhood to adulthood was associated with a greater prevalence, but lower incidence of hypertension. CONCLUSION: Efforts to prevent hypertension among African Americans should consider childhood and current SES status.

Prevalence and awareness of CKD among African Americans: the Jackson Heart Study.

BACKGROUND: Chronic kidney disease (CKD) leads to end-stage renal disease and is a growing epidemic throughout the world. In the United States, African Americans have an incidence of end-stage renal disease 4 times that of whites. STUDY DESIGN: Cross-sectional to examine the prevalence and awareness of CKD in African Americans. SETTING & PARTICIPANTS: Observational cohort in the Jackson Heart Study (JHS). PREDICTOR: CKD was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2), the presence of albuminuria, or dialysis therapy. OUTCOMES & MEASUREMENTS: Data from the JHS were analyzed. Medical history, including disease awareness and drug therapy, anthropometric measurements, and serum and urine samples, were obtained from JHS participants at the baseline visit. Associations between CKD prevalence and awareness and selected demographic, socioeconomic, health care access, and disease status parameters were assessed by using logistic regression models. RESULTS: The prevalence of CKD in the JHS was 20%; CKD awareness was only 15.8%. Older participants had a greater prevalence, but also were more aware of CKD. Hypertension, diabetes, cardiovascular disease, hypercholesterolemia, hypertriglyceridemia, increasing age and waist circumference, and being single or less physically active were associated with CKD. Only advancing CKD stage was associated with awareness. LIMITATIONS: Cross-sectional assessment, single urine measurement. CONCLUSIONS: The JHS has a high prevalence and low awareness of CKD, especially in those with less severe disease status. This emphasizes the need for earlier diagnosis and increased education of health care providers and the general population.

Social environmental stressors, psychological factors, and kidney disease.

Kidney disease is one of the most striking examples of health disparities in American public health. Disparities in the prevalence and progression of kidney disease are generally thought to be a function of group differences in the prevalence of kidney disease risk factors such as diabetes, hypertension, and obesity. However, the presence of these comorbidities does not completely explain the elevated rate of progression from chronic kidney disease (CKD) to end-stage renal disease among high-risk populations such as African Americans. We believe that the social environment is an important element in the pathway from CKD risk factors to CKD and end-stage renal disease. This review of the literature draws heavily from social science and social epidemiology to present a conceptual frame specifying how social, economic, and psychosocial factors interact to affect the risks for and the progression of kidney disease.