A multilevel model of postmenopausal breast cancer incidence

BACKGROUND

Breast cancer has a complex etiology that includes genetic, biologic, behavioral, environmental, and social factors. Etiologic factors are frequently studied in isolation with adjustment for confounding, mediating, and moderating effects of other factors. A complex systems model approach may present a more comprehensive picture of the multifactorial etiology of breast cancer.

METHODS

We took a transdisciplinary approach with experts from relevant fields to develop a conceptual model of the etiology of postmenopausal breast cancer. The model incorporated evidence of both the strength of association and the quality of the evidence. We operationalized this conceptual model through a mathematical simulation model with a subset of variables, namely, age, race/ethnicity, age at menarche, age at first birth, age at menopause, obesity, alcohol consumption, income, tobacco use, use of hormone therapy (HT), and BRCA1/2 genotype.

RESULTS

In simulating incidence for California in 2000, the separate impact of individual variables was modest, but reduction in HT, increase in the age at menarche, and to a lesser extent reduction in excess BMI >30 kg/m(2) were more substantial.

CONCLUSIONS

Complex systems models can yield new insights on the etiologic factors involved in postmenopausal breast cancer. Modification of factors at a population level may only modestly affect risk estimates, while still having an important impact on the absolute number of women affected.

IMPACT

This novel effort highlighted the complexity of breast cancer etiology, revealed areas of challenge in the methodology of developing complex systems models, and suggested additional areas for further study.

Dietary intake, plasma homocysteine, and repetitive element DNA methylation in the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

DNA methylation of repetitive elements may explain the relations between dietary intake, hyperhomocysteinemia, and cardiovascular disease risk. We investigated associations of methyl micronutrient intake and plasma total homocysteine with LINE-1 and Alu methylation in a cross-sectional study of 987 adults aged 45-84 y who participated in the Multi-Ethnic Study of Atherosclerosis (MESA) Stress Study.

METHODS AND RESULTS

DNA methylation was estimated using pyrosequencing technology. A 120-item food frequency questionnaire was used to ascertain daily intake of folate, vitamin B12, vitamin B6, zinc, and methionine. Plasma total homocysteine was quantified using a fluorescence polarization immunoassay. Associations of micronutrient intake and homocysteine with LINE-1 and Alu methylation were examined using linear regression. Adjusted differences in %5-methylated cytosines (%5 mC) were examined by categories of predictors using multivariable linear regression models. Intake of methyl-donor micronutrients was not associated with DNA methylation. After adjustment for covariates, each 3 μmol/L increment of homocysteine corresponded with 0.06 (-0.01, 0.13) %5 mC higher LINE-1 methylation. Additionally, BMI was positively associated with LINE-1 methylation (P trend = 0.03). Participants with BMI ≥ 40 kg/m² had 0.35 (0.03, 0.67) %5 mC higher LINE-1 than those with normal BMI. We also observed a 0.10 (0.02, 0.19) %5 mC difference in Alu methylation per 10 cm of height. These associations did not differ by sex.

CONCLUSION

Dietary intake of methyl-donor micronutrients was not associated with measures of DNA methylation in our sample. However, higher BMI was related to higher LINE-1 methylation, and height was positively associated with Alu methylation.

The neighborhood energy balance equation: does neighborhood food retail environment + physical activity environment = obesity? The CARDIA study

BACKGROUND

Recent obesity prevention initiatives focus on healthy neighborhood design, but most research examines neighborhood food retail and physical activity (PA) environments in isolation. We estimated joint, interactive, and cumulative impacts of neighborhood food retail and PA environment characteristics on body mass index (BMI) throughout early adulthood.

METHODS AND FINDINGS

We used cohort data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study [n=4,092; Year 7 (24-42 years, 1992-1993) followed over 5 exams through Year 25 (2010-2011); 12,921 person-exam observations], with linked time-varying geographic information system-derived neighborhood environment measures. Using regression with fixed effects for individuals, we modeled time-lagged BMI as a function of food and PA resource density (counts per population) and neighborhood development intensity (a composite density score). We controlled for neighborhood poverty, individual-level sociodemographics, and BMI in the prior exam; and included significant interactions between neighborhood measures and by sex. Using model coefficients, we simulated BMI reductions in response to single and combined neighborhood improvements. Simulated increase in supermarket density (from 25(th) to 75(th) percentile) predicted inter-exam reduction in BMI of 0.09 kg/m(2) [estimate (95% CI): -0.09 (-0.16, -0.02)]. Increasing commercial PA facility density predicted BMI reductions up to 0.22 kg/m(2) in men, with variation across other neighborhood features [estimate (95% CI) range: -0.14 (-0.29, 0.01) to -0.22 (-0.37, -0.08)]. Simultaneous increases in supermarket and commercial PA facility density predicted inter-exam BMI reductions up to 0.31 kg/m(2) in men [estimate (95% CI) range: -0.23 (-0.39, -0.06) to -0.31 (-0.47, -0.15)] but not women. Reduced fast food restaurant and convenience store density and increased public PA facility density and neighborhood development intensity did not predict reductions in BMI.

CONCLUSIONS

Findings suggest that improvements in neighborhood food retail or PA environments may accumulate to reduce BMI, but some neighborhood changes may be less beneficial to women.

Perceived neighborhood problems: multilevel analysis to evaluate psychometric properties in a Southern adult Brazilian population

Background

Physical attributes of the places in which people live, as well as their perceptions of them, may be important health determinants. The perception of place in which people dwell may impact on individual health and may be a more telling indicator for individual health than objective neighborhood characteristics. This paper aims to evaluate psychometric and ecometric properties of a scale on the perceptions of neighborhood problems in adults from Florianopolis, Southern Brazil.

Methods

Individual, census tract level (per capita monthly familiar income) and neighborhood problems perception (physical and social disorders) variables were investigated. Multilevel models (items nested within persons, persons nested within neighborhoods) were run to assess ecometric properties of variables assessing neighborhood problems.

Results

The response rate was 85.3%, (1,720 adults). Participants were distributed in 63 census tracts. Two scales were identified using 16 items: Physical Problems and Social Disorder. The ecometric properties of the scales satisfactory: 0.24 to 0.28 for the intra-class correlation and 0.94 to 0.96 for reliability. Higher values on the scales of problems in the physical and social domains were associated with younger age, more length of time residing in the same neighborhood and lower census tract income level.

Conclusions

The findings support the usefulness of these scales to measure physical and social disorder problems in neighborhoods.

Air pollution and individual and neighborhood socioeconomic status: evidence from the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Although research has shown that low socioeconomic status (SES) and minority communities have higher exposure to air pollution, few studies have simultaneously investigated the associations of individual and neighborhood SES with pollutants across multiple sites.

OBJECTIVES

We characterized the distribution of ambient air pollution by both individual and neighborhood SES using spatial regression methods.

METHODS

The study population comprised 6,140 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). Year 2000 annual average ambient PM2.5 and NOx concentrations were calculated for each study participant's home address at baseline examination. We investigated individual and neighborhood (2000 U.S. Census tract level) SES measures corresponding to the domains of income, wealth, education, and occupation. We used a spatial intrinsic conditional autoregressive model for multivariable analysis and examined pooled and metropolitan area-specific models.

RESULTS

A 1-unit increase in the z-score for family income was associated with 0.03-μg/m3 lower PM2.5 (95% CI: -0.05, -0.01) and 0.93% lower NOx (95% CI: -1.33, -0.53) after adjustment for covariates. A 1-SD-unit increase in the neighborhood's percentage of persons with at least a high school degree was associated with 0.47-μg/m3 lower mean PM2.5 (95% CI: -0.55, -0.40) and 9.61% lower NOx (95% CI: -10.85, -8.37). Metropolitan area-specific results exhibited considerable heterogeneity. For example, in New York, high-SES neighborhoods were associated with higher concentrations of pollution.

CONCLUSIONS

We found statistically significant associations of SES measures with predicted air pollutant concentrations, demonstrating the importance of accounting for neighborhood- and individual-level SES in air pollution health effects research.

Air pollution and individual and neighborhood socioeconomic status: evidence from the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Although research has shown that low socioeconomic status (SES) and minority communities have higher exposure to air pollution, few studies have simultaneously investigated the associations of individual and neighborhood SES with pollutants across multiple sites.

OBJECTIVES

We characterized the distribution of ambient air pollution by both individual and neighborhood SES using spatial regression methods.

METHODS

The study population comprised 6,140 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). Year 2000 annual average ambient PM2.5 and NOx concentrations were calculated for each study participant's home address at baseline examination. We investigated individual and neighborhood (2000 U.S. Census tract level) SES measures corresponding to the domains of income, wealth, education, and occupation. We used a spatial intrinsic conditional autoregressive model for multivariable analysis and examined pooled and metropolitan area-specific models.

RESULTS

A 1-unit increase in the z-score for family income was associated with 0.03-μg/m3 lower PM2.5 (95% CI: -0.05, -0.01) and 0.93% lower NOx (95% CI: -1.33, -0.53) after adjustment for covariates. A 1-SD-unit increase in the neighborhood's percentage of persons with at least a high school degree was associated with 0.47-μg/m3 lower mean PM2.5 (95% CI: -0.55, -0.40) and 9.61% lower NOx (95% CI: -10.85, -8.37). Metropolitan area-specific results exhibited considerable heterogeneity. For example, in New York, high-SES neighborhoods were associated with higher concentrations of pollution.

CONCLUSIONS

We found statistically significant associations of SES measures with predicted air pollutant concentrations, demonstrating the importance of accounting for neighborhood- and individual-level SES in air pollution health effects research.

Associations of organic produce consumption with socioeconomic status and the local food environment: Multi-Ethnic Study of Atherosclerosis (MESA)

Neighborhood characteristics, such as healthy food availability, have been associated with consumption of healthy food. Little is known about the influence of the local food environment on other dietary choices, such as the decision to consume organic food. We analyzed the associations between organic produce consumption and demographic, socioeconomic and neighborhood characteristics in 4,064 participants aged 53-94 in the Multi-Ethnic Study of Atherosclerosis using log-binomial regression models. Participants were classified as consuming organic produce if they reported eating organic fruits and vegetables either "sometimes" or "often or always". Women were 21% more likely to consume organic produce than men (confidence interval [CI]: 1.12-1.30), and the likelihood of organic produce consumption was 13% less with each additional 10 years of age (CI: 0.84-0.91). Participants with higher education were significantly more likely to consume organic produce (prevalence ratios [PR] were 1.05 with a high school education, 1.39 with a bachelor's degree and 1.68 with a graduate degree, with less than high school as the reference group [1.00]). Per capita household income was marginally associated with produce consumption (p = 0.06), with the highest income category more likely to consume organic produce. After adjustment for these individual factors, organic produce consumption was significantly associated with self-reported assessment of neighborhood produce availability (PR: 1.07, CI: 1.02-1.11), with an aggregated measure of community perception of the local food environment (PR: 1.08, CI: 1.00-1.17), and, to a lesser degree, with supermarket density (PR: 1.02: CI: 0.99-1.05). This research suggests that both individual-level characteristics and qualities of the local food environment are associated with having a diet that includes organic food.

Examining the association between salivary cortisol levels and subclinical measures of atherosclerosis: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

To investigate the association between salivary cortisol and two markers of subclinical cardiovascular disease (CVD), coronary calcification (CAC), and ankle-brachial index (ABI).

METHODS

Data from an ancillary study to the Multi-Ethnic Study of Atherosclerosis (MESA), the MESA Stress Study, were used to analyze associations of salivary cortisol data collected six times per day over three days with CAC and ABI. The authors used mixed models with repeat cortisol measures nested within persons to determine if specific features of the cortisol profile were associated with CAC and ABI.

RESULTS

A total of 464 participants were included in the CAC analysis and 610 in the ABI analysis. The mean age of participants was 65.6 years. A 1-unit increase in log coronary calcium was associated with a 1.77% flatter early decline in cortisol (95% CI: 0.23, 3.34) among men and women combined. Among women low ABI was associated with a steeper early decline (-13.95% CI: -25.58, -3.39) and a marginally statistically significant flatter late decline (1.39% CI: -0.009, 2.81). The cortisol area under the curve and wake to bedtime slope were not associated with subclinical CVD.

CONCLUSIONS

This study provides weak support for the link between cortisol and measures of subclinical atherosclerosis. We found an association between some features of the diurnal cortisol profile and coronary calcification and ABI but associations were not consistent across subclinical measures. There are methodological challenges in detecting associations of cortisol measures at a point in time with health outcomes that develop over a lifetime. Studies of short-term mechanisms linking stress to physiological processes related to the development of early atherosclerosis may be more informative.

Socioeconomic status, John Henryism and blood pressure among African-Americans in the Jackson Heart Study

John Henryism connotes a strong behavioral predisposition to engage in effortful, active coping with difficult social and economic stressors. This behavioral predisposition is measured by the 12 item John Henryism Scale for Active Coping (JHAC). The John Henry hypothesis predicts that the well-known inverse socioeconomic status (SES)-blood pressure association will be stronger among persons who score high rather than low on the JHAC. We tested this hypothesis in a large African American cohort using baseline data from the Jackson Heart Study. Unlike previous studies, we used multiple indicators of SES: income, education, occupation, childhood SES and cumulative SES. Because the hypothesis is most relevant for adults still in the labor force, we excluded retired participants, yielding a sample size of 3978. Gender-specific Poisson regression models for hypertension adjusting for age, John Henryism, SES, and a John Henryism-SES interaction term, were fit to examine associations. Separate models were fit for each SES indicator. We found some evidence that John Henryism modified the association between income and hypertension in men: low income was associated with higher prevalence of hypertension in men who scored high on John Henryism (prevalence ratio (PR) for low vs. high income tertile 1.12), but with lower hypertension prevalence among men who scored low on John Henryism (PR 0.85, one sided P value for multiplicative interaction <0.05). For women, the association of low income with higher hypertension prevalence was stronger at lower than higher levels of John Henryism (PR 1.27 and 1.06 at low and high levels of John Henryism respectively, P value<0.05). There was no evidence that John Henryism modified the associations of hypertension with other SES indicators in men or women. The modest support of the John Henryism Hypothesis in men only, adds to the literature on this subject, but underscores questions regarding the gender, spatial, socioeconomic and historical contexts in which the hypothesis is valid.

Using an agent-based model to simulate children's active travel to school

Background

Despite the multiple advantages of active travel to school, only a small percentage of US children and adolescents walk or bicycle to school. Intervention studies are in a relatively early stage and evidence of their effectiveness over long periods is limited. The purpose of this study was to illustrate the utility of agent-based models in exploring how various policies may influence children’s active travel to school.

Methods

An agent-based model was developed to simulate children’s school travel behavior within a hypothetical city. The model was used to explore the plausible implications of policies targeting two established barriers to active school travel: long distance to school and traffic safety. The percent of children who walk to school was compared for various scenarios.

Results

To maximize the percent of children who walk to school the school locations should be evenly distributed over space and children should be assigned to the closest school. In the case of interventions to improve traffic safety, targeting a smaller area around the school with greater intensity may be more effective than targeting a larger area with less intensity.

Conclusions

Despite the challenges they present, agent based models are a useful complement to other analytical strategies in studying the plausible impact of various policies on active travel to school.

Current employment status, occupational category, occupational hazard exposure and job stress in relation to telomere length: the Multiethnic Study of Atherosclerosis (MESA)

OBJECTIVE

Telomere length has been proposed as a biomarker of cell senescence, which is associated with a wide array of adverse health outcomes. While work is a major determinant of health, few studies have investigated the association of telomere length with various dimensions of occupation. Accelerated cellular aging could be a common pathway linking occupational exposure to several health outcomes.

METHODS

Leukocyte telomere length was assessed using quantitative PCR in a community-based sample of 981 individuals (age: 45-84 years). Questionnaires were used to collect information on current employment status, current or main occupation before retirement and job strain. The Occupational Resource Network (O*NET) database was linked to the questionnaire data to create five exposure measures: physical activity on the job, physical hazard exposure, interpersonal stressors, job control and job demands. Linear regression was used to estimate associations of occupational characteristics with telomere lengths after adjustment for age, sex, race, socioeconomic position and several behavioural risk factors.

RESULTS

There were no mean differences in telomere lengths across current employment status, occupational category, job strain categories or levels of most O*NET exposure measures. There was also no evidence that being in lower status occupational categories or being exposed to higher levels of adverse physical or psychosocial exposures accelerated the association between age and telomere shortening.

CONCLUSIONS

Cellular aging as reflected by shorter telomeres does not appear to be an important pathway linking occupation to various health outcomes.

A genome-wide association study of depressive symptoms

BACKGROUND

Depression is a heritable trait that exists on a continuum of varying severity and duration. Yet, the search for genetic variants associated with depression has had few successes. We exploit the entire continuum of depression to find common variants for depressive symptoms.

METHODS

In this genome-wide association study, we combined the results of 17 population-based studies assessing depressive symptoms with the Center for Epidemiological Studies Depression Scale. Replication of the independent top hits (p<1×10(-5)) was performed in five studies assessing depressive symptoms with other instruments. In addition, we performed a combined meta-analysis of all 22 discovery and replication studies.

RESULTS

The discovery sample comprised 34,549 individuals (mean age of 66.5) and no loci reached genome-wide significance (lowest p = 1.05×10(-7)). Seven independent single nucleotide polymorphisms were considered for replication. In the replication set (n = 16,709), we found suggestive association of one single nucleotide polymorphism with depressive symptoms (rs161645, 5q21, p = 9.19×10(-3)). This 5q21 region reached genome-wide significance (p = 4.78×10(-8)) in the overall meta-analysis combining discovery and replication studies (n = 51,258).

CONCLUSIONS

The results suggest that only a large sample comprising more than 50,000 subjects may be sufficiently powered to detect genes for depressive symptoms.

Assessing the psychometric and ecometric properties of neighborhood scales in developing countries: Saúde em Beagá Study, Belo Horizonte, Brazil, 2008-2009

Although specific measurement instruments are necessary to better understand the relationship between features of neighborhoods and health, very few studies have developed instruments to measure neighborhood features in developing countries. The objective of the study was to develop valid and reliable measures of neighborhood context useful in a Latin American urban context, assess their psychometric and ecometric properties, and examine individual and neighborhood-level predictors of these measures. We analyzed data from a multistage household survey (2008-2009) conducted in Belo Horizonte City by the Observatory for Urban Health. One adult in each household was selected to answer a questionnaire that included scales to measure neighborhood domains. Census tracts were used to proxy neighborhoods. Internal consistency was evaluated by Cronbach's alpha, and multilevel models were used to estimate ecometric properties and to estimate associations of neighborhood measures with socioeconomic indicators. The final sample comprised 4048 survey respondents representing 149 census tracts. We assessed ten neighborhood environment dimensions: public services, aesthetic quality, walking environment, safety, violence, social cohesion, neighborhood participation, neighborhood physical disorder, neighborhood social disorder, and neighborhood problems. Cronbach's alpha coefficients ranged from 0.53 to 0.83; intraneighborhood correlations ranged from 0.02 to 0.53, and neighborhood reliability varied from 0.76 to 0.99. Most scales were associated with individual and neighborhood socioeconomic predictors. Questionnaires can be used to reliably measure neighborhood contexts in developing countries.

Socioeconomic factors and leukocyte telomere length in a multi-ethnic sample: findings from the multi-ethnic study of atherosclerosis (MESA)

Previous findings have linked lower socioeconomic status (SES) with elevated morbidity and mortality. Leukocyte telomere length (LTL), which also has been associated with age-related disease morbidity and mortality, is a marker of aging at the cellular level, making it a valuable early biomarker of risk and an indicator of biological age. It is hypothesized that SES will be associated with LTL, indicating that SES influences disease risk by accelerating biological aging. In the present sample we test for associations of childhood SES and adult SES (i.e. education, income, home ownership) with LTL, and examine whether these associations vary by racial/ethnic group. Analyses on 963 subjects (18.7% White, 53% Hispanics, and 28.5% African American) from the stress ancillary study of the multi-ethnic study of atherosclerosis revealed a significant difference in LTL between home owners and renters in Hispanic and White participants (p<.05), but not amongst African Americans (p=.98). There were no linear associations of adult education or family income with LTL, however, there was an inverse association between father's education and LTL (p=.03). These findings suggest that for Whites and Hispanics renting vs. owning a home is associated with an older biological age; however we did not replicate previous findings linking education with LTL.

Social factors and leukocyte DNA methylation of repetitive sequences: the multi-ethnic study of atherosclerosis

Epigenetic changes are a potential mechanism contributing to race/ethnic and socioeconomic disparities in health. However, there is scant evidence of the race/ethnic and socioeconomic patterning of epigenetic marks. We used data from the Multi-Ethnic Study of Atherosclerosis Stress Study (N = 988) to describe age- and gender- independent associations of race/ethnicity and socioeconomic status (SES) with methylation of Alu and LINE-1 repetitive elements in leukocyte DNA. Mean Alu and Line 1 methylation in the full sample were 24% and 81% respectively. In multivariable linear regression models, African-Americans had 0.27% (p<0.01) and Hispanics 0.20% (p<0.05) lower Alu methylation than whites. In contrast, African-Americans had 0.41% (p<0.01) and Hispanics 0.39% (p<0.01) higher LINE-1 methylation than whites. These associations remained after adjustment for SES. In addition, a one standard deviation higher wealth was associated with 0.09% (p<0.01) higher Alu and 0.15% (p<0.01) lower LINE-1 methylation in age- and gender- adjusted models. Additional adjustment for race/ethnicity did not alter this pattern. No associations were observed with income, education or childhood SES. Our findings, from a large community-based sample, suggest that DNA methylation is socially patterned. Future research, including studies of gene-specific methylation, is needed to understand better the opposing associations of Alu and LINE-1 methylation with race/ethnicity and wealth as well as the extent to which small methylation changes in these sequences may influence disparities in health.

Socioeconomic characteristics of residential areas and risk of death: is variation in spatial units for analysis a source of heterogeneity in observed associations?

OBJECTIVES

Evidence on the association between the adverse socioeconomic characteristics of residential area and mortality is mixed. We examined whether the choice of spatial unit is critical in detecting this association.

DESIGN

Register-linkage study.

SETTING

Data were from the Finnish Public Sector study's register cohort.

PARTICIPANTS

The place of residence of 146 600 cohort participants was linked to map grids and administrative areas, and they were followed up for mortality from 2000 to 2011. Residential area socioeconomic deprivation and household crowding were aggregated into five alternative areas based on map grids (250×250 m, 1×1 km and 10×10 km squares), and administrative borders (zip-code area and town).

PRIMARY AND SECONDARY OUTCOME MEASURES

All-cause mortality.

RESULTS

For the 250×250 m area, mortality risk increased with increasing socioeconomic deprivation (HR for top vs bottom quintile 1.36, 95% CI 1.21 to 1.52). This association was either weaker or missing when broader spatial units were used. For household crowding, excess mortality was observed across all spatial units, the HRs ranging from 1.14 (95% CI 1.03 to 1.25) for zip code, and 1.21 (95% CI 1.11 to 1.31) for 250×250 m areas to 1.28 (95% CI 1.10 to 1.50) for 10×10 km areas.

CONCLUSIONS

Variation in spatial units for analysis is a source of heterogeneity in observed associations between residential area characteristics and risk of death.

Modeling the salivary cortisol profile in population research: the multi-ethnic study of atherosclerosis

In many studies, it has been hypothesized that stress and its biologic consequences may contribute to disparities in rates of cardiovascular disease. However, understanding of the most appropriate statistical methods to analyze biologic markers of stress, such as salivary cortisol, remains limited. The authors explore the utility of various statistical methods in modeling daily cortisol profiles in population-based studies. They demonstrate that the proposed methods allow additional insight into the cortisol profile compared with commonly used summaries of the profiles based on raw data. For instance, one can gain insights regarding the shape of the population average curve, characterize the types of individual-level departures from the average curve, and better understand the relation between covariates and attained cortisol levels or slopes at various points of the day, in addition to drawing inferences regarding common features of the cortisol profile, such as the cortisol awakening response and the area under the curve. The authors compare the inference and interpretations drawn from these methods and use data collected as part of the Multi-Ethnic Study of Atherosclerosis to illustrate them.

Racial discrimination, racial/ethnic segregation, and health behaviors in the CARDIA study

OBJECTIVE

Racial discrimination has been associated with unhealthy behaviors, but the mechanisms responsible for these associations are not understood and may be related to residential racial segregation. We investigated associations between self-reported racial discrimination and health behaviors before and after controlling for individual- and neighborhood-level characteristics; and potential effect modification of these associations by segregation.

DESIGN

We used data from the longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) study for 1169 African-Americans and 1322 whites. To assess racial discrimination, we used a four category variable to capture the extent and persistence of self-reported discrimination between examination at years 7 (1992-1993) and 15 (2000-2001). We assessed smoking status, alcohol consumption, and physical activity at year 20 (2005-2006). Segregation was examined as the racial/ethnic composition at the Census tract level.

RESULTS

Discrimination was more common in African-Americans (89.1%) than in whites (40.0%). Living in areas with high percentage of blacks was associated with less reports of discrimination in African-Americans but more reports in whites. After adjustment for selected characteristics including individual- and neighborhood-level socioeconomic conditions and segregation, we found significant positive associations of discrimination with smoking and alcohol consumption in African-Americans and with smoking in whites. African-Americans experiencing moderate or high discrimination were more physically active than those reporting no discrimination. Whites reporting some discrimination were also more physically active than those reporting no discrimination. We observed no interactions between discrimination and segregation measures in African-Americans or whites for any of the three health behaviors.

CONCLUSIONS

Racial discrimination may impact individuals' adoption of healthy and unhealthy behaviors independent of racial/ethnic segregation. These behaviors may help individuals buffer or reduce the stress of discrimination.

The contribution of stress to the social patterning of clinical and subclinical CVD risk factors in African Americans: the Jackson Heart Study

It is often hypothesized that psychosocial stress may contribute to associations of socioeconomic position (SEP) with risk factors for cardiovascular disease (CVD). However, few studies have investigated this hypothesis among African Americans, who may be more frequently exposed to stressors due to social and economic circumstances. Cross-sectional data from the Jackson Heart Study (JHS), a large population-based cohort of African Americans, were used to examine the contributions of stressors to the association of SEP with selected cardiovascular (CVD) risk factors and subclinical atherosclerotic disease. Among women, higher income was associated with lower prevalence of hypertension, obesity, diabetes and carotid plaque and lower levels of stress. Higher stress levels were also weakly, albeit positively, associated with hypertension, diabetes, and obesity, but not with plaque. Adjustment for the stress measures reduced the associations of income with hypertension, diabetes and obesity by a small amount that was comparable to, or larger, than the reduction observed after adjustment for behavioral risk factors. In men, high income was associated with lower prevalence of diabetes and stressors were not consistently associated with any of the outcomes examined. Overall, modest mediation effects of stressors were observed for diabetes (15.9%), hypertension (9.7%), and obesity (5.1%) among women but only results for diabetes were statistically significant. No mediation effects of stressors were observed in men. Our results suggest that stressors may partially contribute to associations of SEP with diabetes and possibly hypertension and obesity in African American women. Further research with appropriate study designs and data is needed to understand the dynamic and interacting effects of stressors and behaviors on CVD outcomes as well as sex differences in these effects.

Walking distance by trip purpose and population subgroups

BACKGROUND

Walking distance is an important concept in the fields of transportation and public health. A distance of 0.25 miles is often used as an acceptable walking distance in U.S. research studies. Overall, research on the distance and duration of walking trips for different purposes and across different population groups remains limited.

PURPOSE

This study examines the prevalence of walking and distances and durations of walking trips for different purposes among U.S. residents.

METHODS

The distances and durations of walking trips for different purposes across population groups were compared using nationally representative data from the 2009 National Household Travel Survey (NHTS). Distance decay functions were used to summarize the distribution of walking distances and durations for different purposes and population subgroups. Data were analyzed in 2011.

RESULTS

Sixteen percent of respondents had at least one daily walking trip. The mean and median values for walking distance were 0.7 and 0.5 miles, respectively. For walking duration, the mean and median values were 14.9 and 10 minutes. About 65% of walking trips were more than 0.25 miles in distance, and about 18% of walking trips were more than 1 mile. Large variations were found among various purposes for both distance and duration. The distances and durations of walking for recreation were substantially longer than those for other purposes. People with lower versus higher household income walked longer distances for work but shorter distances for recreation.

CONCLUSIONS

Only a small fraction of respondents walk, but trips longer than 0.25 miles are common. There is substantial variability in the distance and duration of walking trips by purpose and population subgroups. These differences have implications for developing strategies to increase physical activity through walking.

Reducing violence by transforming neighborhoods: a natural experiment in Medellín, Colombia

Neighborhood-level interventions provide an opportunity to better understand the impact that neighborhoods have on health. In 2004, municipal authorities in Medellín, Colombia, built a public transit system to connect isolated low-income neighborhoods to the city's urban center. Transit-oriented development was accompanied by municipal investment in neighborhood infrastructure. In this study, the authors examined the effects of this exogenous change in the built environment on violence. Neighborhood conditions and violence were assessed in intervention neighborhoods (n = 25) and comparable control neighborhoods (n = 23) before (2003) and after (2008) completion of the transit project, using a longitudinal sample of 466 residents and homicide records from the Office of the Public Prosecutor. Baseline differences between these groups were of the same magnitude as random assignment of neighborhoods would have generated, and differences that remained after propensity score matching closely resembled imbalances produced by paired randomization. Permutation tests were used to estimate differential change in the outcomes of interest in intervention neighborhoods versus control neighborhoods. The decline in the homicide rate was 66% greater in intervention neighborhoods than in control neighborhoods (rate ratio = 0.33, 95% confidence interval: 0.18, 0.61), and resident reports of violence decreased 75% more in intervention neighborhoods (odds ratio = 0.25, 95% confidence interval 0.11, 0.67). These results show that interventions in neighborhood physical infrastructure can reduce violence.

Population structure of Hispanics in the United States: the multi-ethnic study of atherosclerosis

Using ∼60,000 SNPs selected for minimal linkage disequilibrium, we perform population structure analysis of 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By projection of principal components (PCs) of ancestry to samples from the HapMap phase III and the Human Genome Diversity Panel (HGDP), we show the first two PCs quantify the Caucasian, African, and Native American origins, while the third and fourth PCs bring out an axis that aligns with known South-to-North geographic location of HGDP Native American samples and further separates MESA Mexican versus Central/South American samples along the same axis. Using k-means clustering computed from the first four PCs, we define four subgroups of the MESA Hispanic cohort that show close agreement with self-identification, labeling the clusters as primarily Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. To demonstrate our recommendations for genetic analysis in the MESA Hispanic cohort, we present pooled and stratified association analysis of triglycerides for selected SNPs in the LPL and TRIB1 gene regions, previously reported in GWAS of triglycerides in Caucasians but as yet unconfirmed in Hispanic populations. We report statistically significant evidence for genetic association in both genes, and we further demonstrate the importance of considering population substructure and genetic heterogeneity in genetic association studies performed in the United States Hispanic population.

Using genotype data from about 60,000 distinct genetic markers, we examined population structure in 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By comparing genetic ancestry of MESA Hispanic participants to reference samples representing worldwide diversity, we show major differences in ancestry of MESA Hispanics reflecting their Caucasian, African, and Native American origins, with finer differences corresponding to North-South geographic origins that separate MESA Mexican versus Central/South American samples. Based on our analysis, we define four subgroups of the MESA Hispanic cohort that show close agreement with the following self-identified regions of origin: Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. We examine association of triglycerides with selected genetic markers, and we further demonstrate the importance of considering differences in genetic ancestry (or factors associated with genetic ancestry) when performing genetic studies of the United States Hispanic population.

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.

Factorial invariance, scale reliability, and construct validity of the job control and job demands scales for immigrant workers: the multi-ethnic study of atherosclerosis

Immigrants have a different social context from those who stay in their home country or those who were born to the country that immigrants now live. Cultural theory of risk perception suggests that social context influences one's interpretation of questionnaire items. We examined psychometric properties of job control and job demand scales with US- and foreign-born workers who preferred English, Spanish, or Chinese (n = 3,114, mean age = 58.1). Across all groups, the job control scale had acceptable Cronbach's alpha (0.78-0.83) and equivalent factor loadings (ΔCFI < 0.01). Immigrants had low alpha (0.42-0.65) for the job demands scale regardless of language, education, or age of migration. Two job-demand items had different factor loadings across groups. Among immigrants, both scales had inconsistent associations with perceived job stress and self-rated health. For a better understanding of immigrants' job stress, the concept of job demands should be expanded and immigrants' expectations for job control explored.

Sex differences in subclinical atherosclerosis by race/ethnicity in the multi-ethnic study of atherosclerosis

Sex differences in cardiovascular disease mortality are more pronounced among non-Hispanic whites than other racial/ethnic groups, but it is unknown whether this variation is present in the earlier subclinical stages of disease. The authors examined racial/ethnic variation in sex differences in coronary artery calcification (CAC) and carotid intimal media thickness at baseline in 2000-2002 among participants (n = 6,726) in the Multi-Ethnic Study of Atherosclerosis using binomial and linear regression. Models adjusted for risk factors in several stages: age, traditional cardiovascular disease risk factors, behavioral risk factors, psychosocial factors, and adult socioeconomic position. Women had a lower prevalence of any CAC and smaller amounts of CAC when present than men in all racial/ethnic groups. Sex differences in the prevalence of CAC were more pronounced in non-Hispanic whites than in African Americans and Chinese Americans after adjustment for traditional cardiovascular disease risk factors, and further adjustment for behavioral factors, psychosocial factors, and socioeconomic position did not modify these results (for race/sex, P(interaction) = 0.047). Similar patterns were observed for amount of CAC among adults with CAC. Racial/ethnic variation in sex differences for carotid intimal media thickness was less pronounced. In conclusion, coronary artery calcification is differentially patterned by sex across racial/ethnic groups.

Long-term exposure to airborne particles and arterial stiffness: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Increased arterial stiffness could represent an intermediate subclinical outcome in the mechanistic pathway underlying associations between average long-term pollution exposure and cardiovascular events.

OBJECTIVE

We hypothesized that 20 years of exposure to particulate matter (PM) ≤ 2.5 and 10 μm in aerodynamic diameter (PM2.5 and PM10, respectively) would be positively associated with arterial stiffness in 3,996 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) who were seen at six U.S. study sites.

METHODS

We assigned pollution exposure during two decades preceding a clinical exam (2000-2002) using observed PM10 from monitors nearest participants' residences and PM10 and PM2.5 imputed from a space-time model. We examined three log-transformed arterial stiffness outcome measures: Young's modulus (YM) from carotid artery ultrasound and large (C1) and small (C2) artery vessel compliance from the radial artery pulse wave. All associations are expressed per 10 μg/m3 increment in PM and were adjusted for weather, age, sex, race, glucose, triglycerides, diabetes, waist:hip ratio, seated mean arterial pressure, smoking status, pack-years, cigarettes per day, environmental tobacco smoke, and physical activity. C1 and C2 models were further adjusted for heart rate, weight, and height.

RESULTS

Long-term average particle exposure was not associated with greater arterial stiffness measured by YM, C1, or C2, and the few associations observed were not robust across metrics and adjustment schemes.

CONCLUSIONS

Long-term particle mass exposure did not appear to be associated with greater arterial stiffness in this study sample.

Racial/ethnic heterogeneity in the socioeconomic patterning of CVD risk factors: in the United States: the multi-ethnic study of atherosclerosis

Many studies document racial variation, gender differences, and socioeconomic status (SES) patterning in cardiovascular disease (CVD) risk factors but few studies have investigated heterogeneity in SES differences by race/ethnicity or gender. Using data from the Multi-Ethnic Study of Atherosclerosis (N=6,814) and stratified regression models, we investigated race/ethnic differences in the SES patterning of diabetes, hypertension, smoking, and body mass index (BMI). Inverse socioeconomic gradients in hypertension, diabetes, smoking, and BMI were observed in White and Black women but associations were weaker or absent in Hispanic and Chinese women (except in the case of diabetes for Hispanic women). Even greater heterogeneity in social patterning of risk factors was observed in men. In White men all four risk factors were inversely associated with socioeconomic position, although often associations were only present or were stronger for education than for income. The inverse socioeconomic patterning was much less consistent in men of other races/ethnic groups, and higher SES was associated with higher BMI in non-White men. These findings have implications for understanding the causes of social patterning, for the analysis of SES adjusted race/ethnic differences, and for the targeting of interventions.

The influence of persistent pathogens on circulating levels of inflammatory markers: a cross-sectional analysis from the Multi-Ethnic Study of Atherosclerosis

Background

Systemic inflammation is linked to cardiovascular risk, but the influence of persistent pathogens, which are conventionally dichotomously categorized, on circulating levels of inflammatory markers is not clear. Antibody levels of pathogens have not been examined in relation to inflammation.

Methods

Using data from a subsample of the Multi-Ethnic Study of Atherosclerosis, we examined circulating levels of interleukin-6 (IL-6), C-reactive protein (CRP) and fibrinogen in relation to five common persistent pathogens: cytomegalovirus, herpes simplex virus-1, Hepatitis A virus, Helicobacter pylori and Chlamydia pneumoniae. We tested the hypothesis that the number of seropositive pathogens (based on conventional cut-off points) would not be as sensitive a marker of inflammation as immune response measured by antibody levels to pathogens.

Results

High antibody response to multiple pathogens showed graded and significant associations with IL-6 (p < 0.001), CRP (p = 0.04) and fibrinogen (p = 0.001), whereas seropositive pathogen burden did not. In multiple linear regression models, high antibody response to multiple pathogens maintained a positive association only with IL-6 (4.4% per pathogen exhibiting high antibody response, 95% CI 0.0-8.9).

Conclusions

High antibody response to pathogens was a more consistent marker of inflammatory outcomes compared to seropositivity alone and high antibody response to multiple pathogens was a stronger marker compared to any single pathogen.

Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association

In 2004, the first American Heart Association scientific statement on "Air Pollution and Cardiovascular Disease" concluded that exposure to particulate matter (PM) air pollution contributes to cardiovascular morbidity and mortality. In the interim, numerous studies have expanded our understanding of this association and further elucidated the physiological and molecular mechanisms involved. The main objective of this updated American Heart Association scientific statement is to provide a comprehensive review of the new evidence linking PM exposure with cardiovascular disease, with a specific focus on highlighting the clinical implications for researchers and healthcare providers. The writing group also sought to provide expert consensus opinions on many aspects of the current state of science and updated suggestions for areas of future research. On the basis of the findings of this review, several new conclusions were reached, including the following: Exposure to PM <2.5 microm in diameter (PM(2.5)) over a few hours to weeks can trigger cardiovascular disease-related mortality and nonfatal events; longer-term exposure (eg, a few years) increases the risk for cardiovascular mortality to an even greater extent than exposures over a few days and reduces life expectancy within more highly exposed segments of the population by several months to a few years; reductions in PM levels are associated with decreases in cardiovascular mortality within a time frame as short as a few years; and many credible pathological mechanisms have been elucidated that lend biological plausibility to these findings. It is the opinion of the writing group that the overall evidence is consistent with a causal relationship between PM(2.5) exposure and cardiovascular morbidity and mortality. This body of evidence has grown and been strengthened substantially since the first American Heart Association scientific statement was published. Finally, PM(2.5) exposure is deemed a modifiable factor that contributes to cardiovascular morbidity and mortality.

Left ventricular mass and ventricular remodeling among Hispanic subgroups compared with non-Hispanic blacks and whites: MESA (Multi-ethnic Study of Atherosclerosis)

OBJECTIVES

The purpose of this study was to examine the prevalence of left ventricular hypertrophy (LVH) and left ventricular (LV) remodeling patterns within Hispanic subgroups compared with non-Hispanic whites in the MESA (Multi-Ethnic Study of Atherosclerosis).

BACKGROUND

Hispanics are the largest and fastest-growing ethnic minority in the U.S., but there are no data on LVH and LV geometry among Hispanic subgroups.

METHODS

Cardiac magnetic resonance imaging was performed in 4,309 men and women age 45 to 84 years without clinical cardiovascular disease. Hispanics were categorized into subgroups based on self-reported ancestry. LVH was defined as the upper 95th percentile of indexed LV mass in a reference normotensive, nondiabetic, nonobese population, and LV remodeling according to the presence/absence of LVH and abnormal/normal LV mass to LV end-diastolic volume ratio.

RESULTS

Among Hispanic participants, 574 were of Mexican origin, 329 were of Caribbean origin, and 161 were of Central/South American origin. On unadjusted analysis, only Caribbean-origin Hispanics (prevalence ratio = 1.2; 95% confidence interval [CI]: 1.03 to 1.4) had greater prevalence of hypertension than non-Hispanic whites. Hispanic subgroups were more likely to have LVH than non-Hispanic whites after adjustment for hypertension and other covariates (Caribbean-origin Hispanics = odds ratio [OR]: 1.8, 95% CI: 1.1 to 3.0; Mexican-origin Hispanics = OR: 2.2, 95% CI: 1.4 to 3.3; Central/South Americans = OR: 1.5, 95% CI: 0.7 to 3.1). All Hispanic subgroups also had a higher prevalence of concentric and eccentric hypertrophy compared with non-Hispanic whites (p < 0.001).

CONCLUSIONS

Caribbean-origin Hispanics had a higher prevalence of LVH and abnormal LV remodeling compared with non-Hispanic whites. A higher prevalence of LVH and abnormal LV remodeling was also observed among Mexican-origin Hispanics, despite a lower prevalence of hypertension. Differences among Hispanic subgroups regarding LVH and LV remodeling should be taken into account when evaluating cardiovascular risk in this population.

Association of optimism and pessimism with inflammation and hemostasis in the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To investigate the association between optimism/pessimism and concentrations of seven inflammation and hemostasis markers. Optimism and pessimism are associated with cardiovascular disease mortality and progression; however, the biological mechanism remains unclear.

METHODS

This cross-sectional study used data from the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 persons aged 45 to 84 years with no history of clinical cardiovascular disease. The Life-Orientation Test-Revised (LOT-R) was used to measure dispositional optimism and pessimism. Regression analyses were used to estimate associations of optimism and pessimism with interleukin (IL)-6, C-reactive protein (CRP), fibrinogen, homocysteine, Factor VIII, D-dimer, and plasmin-antiplasmin, before and after adjustment for sociodemographics, depression, cynicism, health behaviors, body mass index (BMI), hypertension, and diabetes.

RESULTS

Higher scores on the LOT-R (positive disposition) were related to lower concentrations of IL-6 (p = .001), fibrinogen (p < .001), and homocysteine (p = .031). Associations were stronger for the pessimism subscale. After adjustment for demographics, the percentage differences in inflammatory markers corresponding to a 2-standard deviation increase in pessimism were 6.01% (p = .001) for IL-6, 10.31% (p = .001) for CRP, 2.47% (p < .0001) for fibrinogen, and 1.36% (p = .07) for homocysteine. Associations were attenuated but significant after adjustment for sociodemographics, depression, cynical distrust, and behaviors. Further adjustment for hypertension, BMI, and diabetes reduced associations for CRP and IL-6. Pessimism remained associated with a 1.36% (p = .02) increase in fibrinogen in the fully adjusted model. Factor VIII, D-dimer, and plasmin-antiplasmin were not associated with the LOT-R or subscales.

CONCLUSIONS

Pessimism is related to higher levels of inflammation. Health behaviors, BMI, hypertension, and diabetes seem to play a mediating role.

Mapping community determinants of heat vulnerability

BACKGROUND

The evidence that heat waves can result in both increased deaths and illness is substantial, and concern over this issue is rising because of climate change. Adverse health impacts from heat waves can be avoided, and epidemiologic studies have identified specific population and community characteristics that mark vulnerability to heat waves.

OBJECTIVES

We situated vulnerability to heat in geographic space and identified potential areas for intervention and further research.

METHODS

We mapped and analyzed 10 vulnerability factors for heat-related morbidity/mortality in the United States: six demographic characteristics and two household air conditioning variables from the U.S. Census Bureau, vegetation cover from satellite images, and diabetes prevalence from a national survey. We performed a factor analysis of these 10 variables and assigned values of increasing vulnerability for the four resulting factors to each of 39,794 census tracts. We added the four factor scores to obtain a cumulative heat vulnerability index value.

RESULTS

Four factors explained > 75% of the total variance in the original 10 vulnerability variables: a) social/environmental vulnerability (combined education/poverty/race/green space), b) social isolation, c) air conditioning prevalence, and d) proportion elderly/diabetes. We found substantial spatial variability of heat vulnerability nationally, with generally higher vulnerability in the Northeast and Pacific Coast and the lowest in the Southeast. In urban areas, inner cities showed the highest vulnerability to heat.

CONCLUSIONS

These methods provide a template for making local and regional heat vulnerability maps. After validation using health outcome data, interventions can be targeted at the most vulnerable populations.

Life course socioeconomic conditions and metabolic syndrome in adults: the Atherosclerosis Risk in Communities (ARIC) Study

PURPOSE

This study examined the effect of childhood, adulthood, and cumulative socioeconomic status (cumSES) on the prevalence of metabolic syndrome (MetS) in middle-aged adults in the Atherosclerosis Risk in Communities Study (1987-1989).

METHODS

Participants included 2,461 black and 8,536 white men and women 45 to 64 years of age without diabetes. Socioeconomic status (SES) measures from childhood, early adulthood, and mature adulthood were used to create a cumSES score. Childhood SES, early adult SES, mature adult SES and cumSES scores were grouped into two categories (high/low). Age- and center-adjusted prevalence ratios and 95% confidence intervals for MetS, using the Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III) criteria, by SES were estimated by log-linear regression for race-sex groups.

RESULTS

Black and white women with low childhood SES, early adult SES, mature adult SES or cumSES were more likely to have the MetS than those with high SES. These associations remained after adjustment for physical activity, smoking status, and drinking status. In contrast, there was no association of SES with MetS in men.

CONCLUSIONS

Our findings suggest that socioeconomic disadvantage early in life and across the life course influences risk of the MetS in black and white women.

US local action on heat and health: are we prepared for climate change?

OBJECTIVES

Global climate change is increasing the frequency of heat waves, hot weather, and temperature variability, which contribute to mortality and illness. Baseline information on local efforts to reduce heat vulnerability, including public advisories; minimizing greenhouse gas emissions; and mitigating urban heat islands, is lacking.

METHODS

We designed a survey about local government programs to prevent health problems and reduce heat exposure during heatwaves and administered it to 285 US communities.

RESULTS

Of 70 respondents, 26 indicated that excessive heat events are a significant issue for the local government; 30 had established preventive programs. Local government leadership and public health impacts of heat were cited most frequently as extremely important determinants of preventive programs, followed by implementation costs, economic impacts of hot weather, and greenhouse gas emissions mitigation. Cool paving materials and vegetated roofs were common heat mitigation strategies. Fact sheets and case studies were desired guidance for protecting communities during hot weather.

CONCLUSIONS

New partnerships and financial resources are needed to support more widespread local action to prevent adverse health consequences of climate change and promote environmental sustainability.

Employment status, coronary heart disease, and stroke among women

PURPOSE

To investigate the association of employment status with coronary heart disease (CHD) and ischemic stroke among middle-aged women.

METHODS

Proportional hazards regression was used to assess the association of employment status, incident CHD, and incident ischemic stroke among 7,058 women, ages 45-64 years at baseline (1987-1989), from the Atherosclerosis Risk in Communities Study.

RESULTS

After adjusting for age and race-field center, women employed outside the home had a decreased risk of CHD (hazard ratio [HR], 0.70; 95% confidence interval [95% CI], 0.56-0.86) and ischemic stroke (HR, 0.62; 95% CI, 0.47-0.84) compared with homemakers. Differences in cardiovascular disease risk factors partially accounted for the association of employment status and CHD (HR, 0.79; 95% CI, 0.63-0.99) and stroke (HR, 0.79; 95% CI, 0.58-1.08). Also, modest differences were noted when the results were stratified by education, with employed women having a lower risk of CHD (HR, 0.65; 95% CI, 0.45-0.93) than homemakers among those with less than a high school education.

CONCLUSIONS

Women employed outside of the home had a lower risk of CHD and stroke compared with homemakers and, for CHD, this association was stronger among women with less than a high school education. These findings suggest additional research into the varied occupational experiences of women, socioeconomic status, and health is warranted.

Availability of healthy foods and dietary patterns: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Inadequate availability of healthy foods may be a barrier to achieving recommended diets.

OBJECTIVE

The objective was to study the association between the directly measured availability of healthy foods and diet quality.

DESIGN

We conducted a cross-sectional study of 759 participants from the Baltimore site of the Multi-Ethnic Study of Atherosclerosis. Diet was characterized by using a food-frequency questionnaire and summarized by using 2 empirically derived dietary patterns reflecting low- and high-quality diets. For each participant, the availability of healthy foods was directly assessed by using 3 measures: in all food stores within their census tract, in their closest food store, and in all food stores within 1 mile (1.6 km) of their residence.

RESULTS

Twenty-four percent of the black participants lived in neighborhoods with a low availability of healthy food compared with 5% of white participants (P < 0.01). After adjustment for age, sex, income, and education, a lower availability of healthy foods in the tract of residence or in the closest store was associated with higher scores on the low-quality dietary pattern (P < 0.05). Less consistent associations were observed for the high-quality dietary pattern.

CONCLUSIONS

Healthy foods were less available for black participants. Low availability of healthy foods was associated with a lower-quality diet. The extent to which improvements in the availability of healthy foods results in higher-quality diets deserves further investigation.

Association between language and risk factor levels among Hispanic adults with hypertension, hypercholesterolemia, or diabetes

BACKGROUND

The association of acculturation and cardiovascular risk factor control among populations with high proportions of immigrants has not been well studied.

METHODS

We studied 1,492 Hispanic participants in the Multi-Ethnic Study of Atherosclerosis (MESA) with hypertension, hypercholesterolemia, and/or diabetes. We used linear regression to examine the cross-sectional relationships between acculturation measures and cardiovascular risk factor levels. Outcome measures included systolic blood pressure (mm Hg), fasting low-density lipoprotein (LDL) cholesterol (mg/dL), and fasting blood glucose (mg/dL). Covariates included education, income, health insurance, physical activity, dietary factors, risk factor-specific medication use, duration of medication use, smoking, and body mass index.

RESULTS

There were 580 Hispanics with hypertension, 539 with hypercholesterolemia, and 248 with diabetes. After adjustment for age and gender, Spanish-speaking Hispanics with cardiovascular risk factors had higher systolic blood pressure, fasting LDL cholesterol, and fasting blood glucose compared to English-speaking Hispanics. Differences in systolic blood pressure were accounted for mainly by education, whereas differences in LDL cholesterol were almost entirely accounted for by cholesterol-lowering medication use. Differences in fasting glucose were partly accounted for by socioeconomic variables but were augmented after adjustment for dietary factors. Similar associations were observed between proportion of life in the United States and risk factor levels.

CONCLUSIONS

Among those with cardiovascular risk factors, Hispanics who spoke Spanish at home and lived less time in the United States had worse control of cardiovascular risk factors. Treatment strategies that focus on Hispanics with low levels of acculturation may improve cardiovascular risk factor control.

Association of acculturation levels and prevalence of diabetes in the multi-ethnic study of atherosclerosis (MESA)

OBJECTIVE

The prevalence of type 2 diabetes among Hispanic and Asian Americans is increasing. These groups are largely comprised of immigrants who may be undergoing behavioral and lifestyle changes associated with development of diabetes. We studied the association between acculturation and diabetes in a population sample of 708 Mexican-origin Hispanics, 547 non-Mexican-origin Hispanics, and 737 Chinese participants in the Multi-Ethnic Study of Atherosclerosis (MESA).

RESEARCH DESIGN AND METHODS

Diabetes was defined as fasting glucose >/=126 mg/dl and/or use of antidiabetic medications. An acculturation score was calculated for all participants using nativity, years living in the U.S., and language spoken at home. The score ranged from 0 to 5 (0 = least acculturated and 5 = most acculturated). Relative risk regression was used to estimate the association between acculturation and diabetes.

RESULTS

For non-Mexican-origin Hispanics, the prevalence of diabetes was positively associated with acculturation score, after adjustment for sociodemographics. The prevalence of diabetes was significantly higher among the most acculturated versus the least acculturated non-Mexican-origin Hispanics (prevalence ratio 2.49 [95% CI 1.14-5.44]); the higher the acculturation score is, the higher the prevalence of diabetes (P for trend 0.059). This relationship between acculturation and diabetes was partly attenuated after adjustment for BMI or diet. Diabetes prevalence was not related to acculturation among Chinese or Mexican-origin Hispanics.

CONCLUSIONS

Among non-Mexican-origin Hispanics in MESA, greater acculturation is associated with higher diabetes prevalence. The relation is at least partly mediated by BMI and diet. Acculturation is a factor that should be considered when predictors of diabetes in racial/ethnic groups are examined.

Cumulative life course and adult socioeconomic status and markers of inflammation in adulthood

OBJECTIVE

To examine the association between cumulative life course and adult socioeconomic status (SES) and adult levels of inflammatory risk markers (fibrinogen, white blood cell count (WBC), C-reactive protein (CRP), von Willebrand factor (vWF) and an overall inflammatory score).

DESIGN

Retrospective cohort study.

SETTING

12,681 white and African-American participants in the Atherosclerosis Risk in Communities (ARIC) study and two ancillary studies.

METHODS

Participants provided information on SES and place of residence in childhood and young (30-40 years) and mature (45+) adulthood. Residences were linked to census data for neighbourhood SES information. Multiple imputation (MI) was used for missing data. Linear regression and adjusted geometric means were used to estimate the effects of SES on inflammatory risk marker levels.

RESULTS

Graded, statistically significant associations were observed between greater cumulative life-course exposure to low education and social class and elevated levels of fibrinogen and WBC among white participants. Stronger graded, statistically significant associations were observed between low adult education, social class and neighbourhood SES and elevated inflammatory levels. Associations were weaker and less consistent in African-Americans. Covariate adjustment attenuated results but many associations remained strong.

CONCLUSIONS

Our results suggest that cumulative exposure to adverse SES conditions across the life course and low adult SES are associated with an elevated systemic inflammatory burden in adulthood. Chronic systemic inflammation may be one pathway linking low life-course SES and elevated cardiovascular disease risk.

Socioeconomic position, race/ethnicity, and inflammation in the multi-ethnic study of atherosclerosis

BACKGROUND

Low socioeconomic position is known to be associated with cardiovascular events and atherosclerosis. Reasons for these associations remain a topic of research. Inflammation could be an important mediating mechanism linking socioeconomic position to cardiovascular risk.

METHODS AND RESULTS

This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 men and women 45 to 84 years of age. Race- and ethnicity-stratified regression analyses were used to estimate associations of household income and education with C-reactive protein and interleukin-6 before and after adjustment for infection and medication use, psychosocial factors, behaviors, adiposity, and diabetes mellitus. Low income was associated with higher concentrations of interleukin-6 in all race/ethnic groups. Percent differences associated with 1-SD-lower income were 9% (95% confidence interval [CI], 7 to 11), 6% (95% CI, 1 to 10), 8% (95% CI, 4 to 11), and 8% (95% CI, 3 to 13) for whites, Chinese, blacks, and Hispanics. Low levels of education were associated with higher levels of interleukin-6 only among whites and blacks (percent difference in interleukin-6 associated with 1-SD-lower education: 9% [95% CI, 6 to 12] among Whites, and 7% [95% CI, 3 to 10] among blacks). Similar patterns were observed for C-reactive protein. Adiposity was the single most important factor explaining socioeconomic position associations, especially among blacks and whites. A smaller effect was seen for psychosocial factors and behaviors in all race groups.

CONCLUSIONS

Both household income and education are associated with inflammation, but associations vary across race/ethnic groups. Associations likely result from socioeconomic position patterning of adiposity and other factors.

Airborne particulate matter exposure and urinary albumin excretion: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVES

Understanding mechanistic pathways linking airborne particle exposure to cardiovascular health is important for causal inference and setting environmental standards. We evaluated whether urinary albumin excretion, a subclinical marker of microvascular function which predicts cardiovascular events, was associated with ambient particle exposure.

METHODS

Urinary albumin and creatinine were measured among members of the Multi-Ethnic Study of Atherosclerosis at three visits during 2000-2004. Exposure to PM(2.5) and PM(10) (microg/m(3)) was estimated from ambient monitors for 1 month, 2 months and two decades before visit one. We regressed recent and chronic (20 year) particulate matter (PM) exposure on urinary albumin/creatinine ratio (UACR, mg/g) and microalbuminuria at first examination, controlling for age, race/ethnicity, sex, smoking, second-hand smoke exposure, body mass index and dietary protein (n = 3901). We also evaluated UACR changes and development of microalbuminuria between the first, and second and third visits which took place at 1.5- to 2-year intervals in relation to chronic PM exposure prior to baseline using mixed models.

RESULTS

Chronic and recent particle exposures were not associated with current UACR or microalbuminuria (per 10 microg/m(3) increment of chronic PM(10) exposure, mean difference in log UACR = -0.02 (95% CI -0.07 to 0.03) and relative probability of having microalbuminuria = 0.92 (95% CI 0.77 to 1.08)) We found only weak evidence that albuminuria was accelerated among those chronically exposed to particles: each 10 microg/m(3) increment in chronic PM(10) exposure was associated with a 1.14 relative probability of developing microalbuminuria over 3-4 years, although 95% confidence intervals included the null (95% CI 0.96 to 1.36).

CONCLUSIONS

UACR is not a strong mechanistic marker for the possible influence of air pollution on cardiovascular health in this sample.

Understanding and representing 'place' in health research: a relational approach

Epidemiology, sociology, and geography have been successful in re-establishing interest in the role of place in shaping health and health inequalities. However, some of the relevant empirical research has relied on rather conventional conceptions of space and place and focused on isolating the "independent" contribution of place-level and individual-level factors. This approach may have resulted in an underestimate of the contribution of 'place' to disease risk. In this paper we argue the case for extensive (quantitative) as well as intensive (qualitative) empirical, as well as theoretical, research on health variation that incorporates 'relational', views of space and place. Specifically, we argue that research in place and health should avoid the false dualism of context and composition by recognising that there is a mutually reinforcing and reciprocal relationship between people and place. We explore in the discussion how these theoretical perspectives are beginning to influence empirical research. We argue that these approaches to understanding how place relates to health are important in order to deliver effective, 'contextually sensitive' policy interventions.

Psychosocial factors and inflammation in the multi-ethnic study of atherosclerosis

BACKGROUND

Psychosocial factors are associated with the development and progress of cardiovascular disease, but the pathological mechanisms remain unclear. We examined the associations of psychosocial risk factors for cardiovascular disease with concentrations of inflammatory markers among healthy adults and assessed the extent to which these associations are mediated by behaviors, body mass index (BMI), and diabetes mellitus.

METHODS

This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis, a multisite study of 6814 men and women aged 45 to 84 years. Regression analyses were used to estimate associations of cynical distrust, chronic stress, and depression with serum levels of C-reactive protein, IL-6, and fibrinogen before and after adjustment for socioeconomic position, behaviors, BMI, and diabetes.

RESULTS

Higher levels of cynical distrust were associated with higher levels of inflammatory markers. The percentage differences (95% confidence intervals [CIs]) comparing the 80th and 20th percentiles of the scale were 7% (3%-11%) for IL-6; 9% (2%-16%) for C-reactive protein; and 1.3% (0.1%-2.4%) for fibrinogen. Higher levels of chronic stress were associated with higher concentrations of IL-6 and C-reactive protein. The percentage differences (95% CIs) comparing 2 and 0 ongoing stressful circumstances were 4% (1%-8%) for IL-6 and 5% (1%-11%) for C-reactive protein. Depression was positively associated with the level of IL-6 (percentage difference [95% CI] comparing the Center for Epidemiologic Studies-Depression Scale scores of >or=21 vs <21 was 7% [1%-14%]). Associations of psychosocial factors with inflammatory markers were reduced by 20% to 55% after adjustment for behavioral factors and by 45% to 100% after adjustment for BMI and diabetes, mostly owing to the effect of BMI. No associations remained after controlling for socioeconomic position, behaviors, BMI, and diabetes.

CONCLUSIONS

Psychosocial factors are associated with higher levels of inflammatory markers, most consistently for cynical distrust. Results are compatible with a mediating role of BMI, behaviors, and diabetes.

Early-life and adult socioeconomic status and inflammatory risk markers in adulthood

BACKGROUND

Associations between childhood and adult socioeconomic status (SES) and adult levels of inflammatory markers (C-reactive protein [CRP], fibrinogen, white blood cell count [WBC], and von Willebrand factor [vWF]) were examined in the Atherosclerosis Risk in Communities (ARIC) Study cohort.

METHODS

A total of 12,681 white and African-American participants provided information on SES (via education and social class) and place of residence in childhood and adulthood. Residences were linked to census data for neighborhood SES information. Multiple imputation was used to impute missing data. Hierarchical and linear regression were used to estimate the effects of SES and possible mediation by adult cardiovascular disease (CVD) risk factors.

FINDINGS

Low childhood social class and education were associated with elevated levels of CRP, fibrinogen, WBC, and vWF (increments of 17%, 2%, 4% and 3% for lowest versus highest education in childhood, respectively) among whites. Findings were less consistent among African-Americans. Adult SES was more strongly associated with inflammation than childhood SES. Individual-level SES measures were more consistently associated with inflammation than neighborhood-level measures. Fibrinogen and WBC showed the most consistent associations with SES; the largest changes in inflammation by SES were observed for CRP. Covariate adjustment strongly attenuated these associations. Mediation of the SES-inflammation associations by BMI, smoking and HDL cholesterol (HDL-C) are suggested by these data.

CONCLUSION

Low individual- and neighborhood-level SES in childhood and adulthood are associated with modest increments in adult inflammatory burden. These associations may operate through the influence of low SES on traditional CVD risk factors, especially BMI, smoking and HDL-C.

Cumulative socioeconomic status across the life course and subclinical atherosclerosis

PURPOSE

The purpose of this study is to investigate the relationship between individual-level and neighborhood-level socioeconomic status (SES) across the life course and subclinical atherosclerosis.

METHODS

Participants from the Atherosclerosis Risk in Communities Study (n=12,332) were queried about individual-level SES and residential addresses across the life course. Individual-level measures were scored and summed to obtain a summary score (I-CumSES), whereas residential addresses were geocoded and linked to census data to obtain a summary neighborhood z score (N-CumSES) to evaluate the association of SES with intima-media thickness (IMT) and peripheral arterial disease (PAD).

RESULTS

A 1-SD lower I-CumSES was associated with greater mean IMT in each race-sex group and greater odds of PAD in white men (odds ratio [OR], 1.28; 95% confidence interval [CI], 0.99-1.64), white women (OR, 1.18; 95% CI, 1.02-1.36), and black women (OR, 1.33; 95% CI, 1.00-1.76). Compared with the highest tertile of N-CumSES, the lowest tertile was associated with greater mean IMT among whites, but was not associated with PAD for whites or blacks. When I-CumSES and N-CumSES were considered simultaneously, associations remained for only I-CumSES and were attenuated after adjustment for cardiovascular disease (CVD) risk factors.

CONCLUSIONS

Lower cumulative individual-level SES across the life course was associated with a greater burden of subclinical atherosclerosis, and this association was mediated in part by CVD risk factors.

Self-reported health, perceived racial discrimination, and skin color in African Americans in the CARDIA study

This study investigates the association between self-reported physical and mental health and both perceived racial discrimination and skin color in African American men and women. We used data from the longitudinal coronary artery risk development in young adults study (CARDIA) in African American men and women (n=1722) in the USA. We assessed self-reported mental and physical health status and depressive symptoms at the Year 15 (2000-2001) follow-up examination using the Medical Outcomes Study Short Form (SF-12) and the Center for Epidemiologic Studies Depression scale. Skin color was measured at the Year 7 examination (1992-1993). To assess racial discrimination, we used a summary score (range 0-21) for 7 questions on experiencing racial discrimination: at school, getting a job, getting housing, at work, at home, getting medical care, on the street or in a public setting. Self-reported racial discrimination was more common in men than in women (78.1% versus 73.0%, p<0.05) and in those with higher educational attainment, independent of gender. Discrimination was statistically significantly associated with worse physical and mental health in both men and women, before and after adjustment for age, education, income, and skin color. For example, mental health (0-100 scale) decreased an average of 0.29 units per unit increase in racial discrimination score in men; this became 0.32 units after adjustment. There was no association between self-reported physical and mental health and skin color. Further studies of the health consequences of discrimination will require investigation of both the upstream determinants of discrimination and the downstream mechanisms by which perceived discrimination affects health outcomes.

Socioeconomic differences in progression of carotid intima-media thickness in the Atherosclerosis Risk in Communities study

OBJECTIVE

To examine the association of socioeconomic factors with progression of carotid intimal-medial thickness (IMT) in middle-aged adults. Cross-sectional associations of IMT with socioeconomic status (SES) have been demonstrated in middle-aged cohorts. It is unclear whether these factors are associated with progression of IMT.

METHODS AND RESULTS

We examined IMT progression over 9 years among a middle-aged cohort of 12,085 black and white subjects free of cardiovascular disease recruited from 4 US sites participating in the Atherosclerosis Risk in Communities (ARIC) study. Baseline IMT was inversely related to SES among whites and blacks. Repeated measures regression models of IMT progression showed moderate inverse relationships of IMT progression with income in whites so that the difference in 5-year IMT progression rates between the highest and lowest categories was -11.5 microm (CI, -17.4 to -5.6). In contrast, among blacks, this gradient is reversed, with an 11.1 microm (CI, -0.1 to 22.3) difference in 5-year progression between highest and lowest income category. Generally, similar patterns were observed for other socioeconomic indicators. Patterns were not accounted for by baseline cardiovascular risk factors.

CONCLUSIONS

SES is inversely related to IMT progression in middle-aged whites but positively related to IMT progression among middle-aged blacks. These differences do not appear to be attributable to selective attrition or higher IMT among blacks at baseline.

Reliability of self-reported neighborhood characteristics

The majority of studies examining the relation between neighborhood environments and health have used census-based indicators to characterize neighborhoods. These studies have shown that neighborhood socioeconomic characteristics are associated with a range of health outcomes. Establishing if these associations reflect causal relations requires testing hypotheses regarding how specific features of neighborhoods are related to specific health outcomes. However, there is little information on the reliability of neighborhood measures. The purpose of this study was to estimate the reliability of a questionnaire measuring various self-reported measures of the neighborhood environment of possible relevance to cardiovascular disease. The study consisted of a face-to-face and telephone interview administered twice to 48 participants over a 2-week period. The face-to-face and telephone portions of the interview lasted an average of 5 and 11 minutes, respectively. The questionnaire was piloted among a largely Latino and African American study sample recruited from a public hospital setting in New York City. Scales were used to assess six neighborhood domains: aesthetic quality, walking/exercise environment, safety from crime, violence, access to healthy foods, and social cohesion. Cronbach's alpha's ranged from .77 to .94 for the scales corresponding to these domains, with test-retest correlations ranging from 0.78 to 0.91. In addition, neighborhood indices for presence of recreational facilities, quality of recreational facilities, neighborhood participation, and neighborhood problems were examined. Test-retest reliability measures for these indices ranged from 0.73 to 0.91. The results from this study suggested that self-reported neighborhood characteristics can be reliably measured.