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1.  Examining the association between salivary cortisol levels and subclinical measures of atherosclerosis: the Multi-Ethnic Study of Atherosclerosis 
Psychoneuroendocrinology  2012;38(7):1036-1046.
To investigate the association between salivary cortisol and two markers of subclinical cardiovascular disease (CVD), coronary calcification (CAC), and ankle-brachial index (ABI).
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.
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.
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.
PMCID: PMC4020284  PMID: 23146655
salivary cortisol; ankle brachial index; coronary calcification; atherosclerosis; stress; cortisol awakening response; cortisol diurnal pattern; Multi-Ethnic Study of Atherosclerosis
2.  Current employment status, occupational category, occupational hazard exposure, and job stress in relation to telomere length: The Multiethnic Study of Atherosclerosis (MESA) 
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.
Leukocyte telomere length was assessed using quantitative polymerase chain reaction (Q-PCR) in a community-based sample of 981 individuals (age: 45–84 years old). Questionnaires were used to collect information on current employment status, current or main occupation before retirement, and job strain. The O*NET (Occupational Resource Network) database was linked to the questionnaire data to create 5 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 behavioral risk factors.
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.
Cellular aging as reflected by shorter telomeres does not appear to be an important pathway linking occupation to various health outcomes.
PMCID: PMC4068015  PMID: 23686115
3.  Racial discrimination, racial/ethnic segregation and health behaviors in the CARDIA Study 
Ethnicity & health  2012;18(3):227-243.
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.
We used data from the longitudinal Coronary Artery Risk Development in Young Adults study (CARDIA) for 1,169 African-Americans and 1,322 whites. To assess racial discrimination, we used a 4 category variable to capture the extent and persistence of self-reported discrimination between years 7 (1992–93) 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 of the Census tract level.
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.
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.
PMCID: PMC3523091  PMID: 22913715
United States; discrimination; segregation; health behaviors; race/ethnicity; neighborhood characteristics
4.  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.
PMCID: PMC3675718  PMID: 22692842
Epidemiologic methods; Psychometrics; Residence characteristics; Data collection; Self-report; Environment design; Censuses
5.  A Genome-Wide Association Study of Depressive Symptoms 
Hek, Karin | Demirkan, Ayse | Lahti, Jari | Terracciano, Antonio | Teumer, Alexander | Cornelis, Marilyn C. | Amin, Najaf | Bakshis, Erin | Baumert, Jens | Ding, Jingzhong | Liu, Yongmei | Marciante, Kristin | Meirelles, Osorio | Nalls, Michael A. | Sun, Yan V. | Vogelzangs, Nicole | Yu, Lei | Bandinelli, Stefania | Benjamin, Emelia J. | Bennett, David A. | Boomsma, Dorret | Cannas, Alessandra | Coker, Laura H. | de Geus, Eco | De Jager, Philip L. | Diez-Roux, Ana V. | Purcell, Shaun | Hu, Frank B. | Rimma, Eric B. | Hunter, David J. | Jensen, Majken K. | Curhan, Gary | Rice, Kenneth | Penman, Alan D. | Rotter, Jerome I. | Sotoodehnia, Nona | Emeny, Rebecca | Eriksson, Johan G. | Evans, Denis A. | Ferrucci, Luigi | Fornage, Myriam | Gudnason, Vilmundur | Hofman, Albert | Illig, Thomas | Kardia, Sharon | Kelly-Hayes, Margaret | Koenen, Karestan | Kraft, Peter | Kuningas, Maris | Massaro, Joseph M. | Melzer, David | Mulas, Antonella | Mulder, Cornelis L. | Murray, Anna | Oostra, Ben A. | Palotie, Aarno | Penninx, Brenda | Petersmann, Astrid | Pilling, Luke C. | Psaty, Bruce | Rawal, Rajesh | Reiman, Eric M. | Schulz, Andrea | Shulman, Joshua M. | Singleton, Andrew B. | Smith, Albert V. | Sutin, Angelina R. | Uitterlinden, André G. | Völzke, Henry | Widen, Elisabeth | Yaffe, Kristine | Zonderman, Alan B. | Cucca, Francesco | Harris, Tamara | Ladwig, Karl-Heinz | Llewellyn, David J. | Räikkönen, Katri | Tanaka, Toshiko | van Duijn, Cornelia M. | Grabe, Hans J. | Launer, Lenore J. | Lunetta, Kathryn L. | Mosley, Thomas H. | Newman, Anne B. | Tiemeier, Henning | Murabito, Joanne
Biological psychiatry  2013;73(7):10.1016/j.biopsych.2012.09.033.
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.
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.
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).
The results suggest that only a large sample comprising more than 50,000 subjects may be sufficiently powered to detect genes for depressive symptoms.
PMCID: PMC3845085  PMID: 23290196
Center for Epidemiologic Studies Depression Scale; CHARGE consortium; depression; depressive symptoms; genetics; genome-wide association study; meta-analysis
6.  Complex systems thinking and current impasses in health disparities research 
American Journal of Public Health  2011;101(9):1627-1634.
Complex systems approaches have received increasing attention in public health because reductionist approaches yield limited insights in the context of dynamic systems. Most discussions to date have been highly abstract. There is a need to consider the application of complex systems approaches to specific research questions. After briefly reviewing the features of population health problems for which complex systems approaches are most likely to yield new insights, this commentary discusses possible applications of complex systems to health disparities research. It provides illustrative examples of how complex systems approaches may help address unanswered and persistent questions regarding genetic factors, life course processes, place effects, and the impact of upstream policies. It is argued that the concepts and methods of complex systems may help researchers move beyond current impasse points in health disparities research.
PMCID: PMC3154209  PMID: 21778505
7.  Socioeconomic Factors and Leukocyte Telomere Length In A Multi-Ethnic Sample: Findings From The Multi-Ethnic Study of Atherosclerosis (MESA) 
Brain, behavior, and immunity  2012;28:108-114.
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.
PMCID: PMC3544984  PMID: 23142704
Telomere length; childhood SES; socioeconomic status; home ownership; wealth; parental education; cellular aging; biological aging; ethnicity
8.  Low Social Support Is Associated With Shorter Leukocyte Telomere Length in Late Life: Multi-Ethnic Study of Atherosclerosis (MESA) 
Psychosomatic medicine  2013;75(2):10.1097/PSY.0b013e31828233bf.
The primary goal was to test the hypothesis that limited social support (SS) is related to shorter leukocyte telomere length (LTL), particularly in an older adult population.
Cross-sectional analyses were performed on 948 participants at Exam 1 of the Multi-Ethnic Study of Atherosclerosis (MESA), ages 45–84 years (18.4% White, 53.1% Hispanics, and 28.5% African-American). LTL was determined using qPCR and social support was measured with the ENRICHD social support inventory.
Across the entire sample, SS was not associated with LTL (p = .87) after adjusting for demographic (age, gender, race/ethnicity, socioeconomic status), age X gender, age X race, health (body mass index, diabetes, pulse pressure), and lifestyle factors (smoking, physical activity, diet), however the interaction term Age (dichotomized) X SS was significant, p = .001. Stratification by age group revealed a positive association between SS (score range: 5–25) and LTL in the older (65–84 years) B(SE) = .005(.002), p = .007, but not younger participants (45–64 years), p = .12, after adjusting for covariates.
These results from a racially/ethnically diverse community sample of men and women provide initial evidence that low SS is associated with shorter LTL in adults aged 65 and older and is consistent with the hypothesis that social environment may contribute to rates of cellular aging, particularly in late life.
PMCID: PMC3881963  PMID: 23370895
telomere length; social support; cellular aging; loneliness; isolation; older adults
9.  The Relationship Between Neighborhood Poverty and Alcohol Use: Estimation by Marginal Structural Models 
Epidemiology (Cambridge, Mass.)  2010;21(4):482-489.
Previous studies on the relationship of neighborhood disadvantage with alcohol use or misuse have often controlled for individual characteristics on the causal pathway, such as income—thus potentially underestimating the relationship between disadvantage and alcohol consumption.
We used data from the Coronary Artery Risk Development in Young Adults study of 5115 adults aged 18–30 years at baseline and interviewed 7 times between 1985 and 2006. We estimated marginal structural models using inverse probability-of-treatment and censoring weights to assess the association between point-in-time/cumulative exposure to neighborhood poverty (proportion of census tract residents living in poverty) and alcohol use/binging, after accounting for time-dependent confounders including income, education, and occupation.
The log-normal model was used to estimate treatment weights while accounting for highly-skewed continuous neighborhood poverty data. In the weighted model, a one-unit increase in neighborhood poverty at the prior examination was associated with a 86% increase in the odds of binging (OR = 1.86 [95% confidence interval = 1.14–3.03]); the estimate from a standard generalized-estimating-equations model controlling for baseline and time-varying covariates was 1.47 (0.96–2.25). The inverse probability-of-treatment and censoring weighted estimate of the relative increase in the number of weekly drinks in the past year associated with cumulative neighborhood poverty was 1.53 (1.02–2.27); the estimate from a standard model was 1.16 (0.83–1.62).
Cumulative and point-in-time measures of neighborhood poverty are important predictors of alcohol consumption. Estimators that more closely approximate a causal effect of neighborhood poverty on alcohol provided a stronger estimate than estimators from traditional regression models.
PMCID: PMC3897210  PMID: 20498603
10.  The Neighborhood Energy Balance Equation: Does Neighborhood Food Retail Environment + Physical Activity Environment = Obesity? The CARDIA Study 
PLoS ONE  2013;8(12):e85141.
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 25th to 75th percentile) predicted inter-exam reduction in BMI of 0.09 kg/m2 [estimate (95% CI): -0.09 (-0.16, -0.02)]. Increasing commercial PA facility density predicted BMI reductions up to 0.22 kg/m2 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/m2 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.
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.
PMCID: PMC3874030  PMID: 24386458
11.  Modeling the Salivary Cortisol Profile in Population Research 
American Journal of Epidemiology  2012;176(10):918-928.
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.
PMCID: PMC3626059  PMID: 23100245
health disparities; parametric nonlinear models; salivary cortisol; semiparametric regression; stress response
12.  Improving retrospective characterization of the food environment for a large region in the United States during a historic time period 
Health & place  2012;18(6):1341-1347.
Access to healthy foods has received increasing attention due to growing prevalence of obesity and diet-related health conditions yet there are major obstacles in characterizing the local food environment. This study developed a method to retrospectively characterize supermarkets for a single historic year, 2005, in 19 counties in 6 states in the USA using a supermarket chain-name list and two business databases. Data preparation, merging, overlaps, added-value amongst various approaches and differences by census tract area-level socio-demographic characteristics are described. Agreement between two food store databases was modest: 63%. Only 55% of the final list of supermarkets were identified by a single business database and selection criteria that included industry classification codes and sales revenue >=$2 million. The added-value of using a supermarket chain-name list and second business database was identification of an additional 14% and 30% of supermarkets, respectively. These methods are particularly useful to retrospectively characterize access to supermarkets during a historic period and when field observations are not feasible and business databases are used.
PMCID: PMC3501601  PMID: 22883050
Residence characteristics; validity; reliability; food; geography; environment
13.  The Contribution of Stress to the Social Patterning of Clinical and Subclinical CVD Risk Factors in African Americans: The Jackson Heart Study 
Social science & medicine (1982)  2012;75(9):1697-1707.
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.
PMCID: PMC3580180  PMID: 22841454
U.S.A.; Stress; social patterning; cardiovascular disease; risk factors; mediation analysis; African Americans
14.  Air Pollution and Individual and Neighborhood Socioeconomic Status: Evidence from the Multi-Ethnic Study of Atherosclerosis (MESA) 
Environmental Health Perspectives  2013;121(11-12):1325-1333.
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.
Citation: Hajat A, Diez-Roux AV, Adar SD, Auchincloss AH, Lovasi GS, O’Neill MS, Sheppard L, Kaufman JD. 2013. Air pollution and individual and neighborhood socioeconomic status: evidence from the Multi-Ethnic Study of Atherosclerosis (MESA). Environ Health Perspect 121:1325–1333;
PMCID: PMC3855503  PMID: 24076625
15.  Associations of the Local Food Environment with Diet Quality—A Comparison of Assessments based on Surveys and Geographic Information Systems 
American journal of epidemiology  2008;167(8):917-924.
There is growing interest in understanding how food environments affect diet, but characterizing the food environment is challenging. The authors investigated the relation between global diet measures (an empirically derived “fats and processed meats” (FPM) dietary pattern and the Alternate Healthy Eating Index (AHEI)) and three complementary measures of the local food environment: 1) supermarket density, 2) participant-reported assessments, and 3) aggregated survey responses of independent informants. Data were derived from the baseline examination (2000–2002) of the Multi-Ethnic Study of Atherosclerosis, a US study of adults aged 45–84 years. A healthy diet was defined as scoring in the top or bottom quintile of AHEI or FPM, respectively. The probability of having a healthy diet was modeled by each environment measure using binomial regression. Participants with no supermarkets near their homes were 25–46% less likely to have a healthy diet than those with the most stores, after adjustment for age, sex, race/ethnicity, and socioeconomic indicators: The relative probability of a healthy diet for the lowest store density category versus the highest was 0.75 (95% confidence interval: 0.59, 0.95) for the AHEI and 0.54 (95% confidence interval: 0.42, 0.70) for FPM. Similarly, participants living in areas with the worst-ranked food environments (by participants or informants) were 22–35% less likely to have a healthy diet than those in the best-ranked food environments. Efforts to improve diet may benefit from combining individual and environmental approaches.
PMCID: PMC2587217  PMID: 18304960
diet; food; residence characteristics; social class
16.  Home and Work Neighborhood Environments in Relation to Body Mass Index: The Multi-Ethnic Study of Atherosclerosis (MESA) 
Little is known about neighborhood characteristics of workplaces, the extent to which they are independently and synergistically correlated with residential environments, and their impact on health.
This study investigated cross-sectional relationships between home and workplace neighborhood environments with body mass index (BMI) in 1,503 working participants of the Multi-Ethnic Study of Atherosclerosis (MESA) with mean age 59.6 (SD=7.4). Neighborhood features were socioeconomic status (SES), social environment (aesthetic quality, safety, and social cohesion), and physical environment (walking environment, recreational facilities, and food stores) derived from census data, locational data on businesses, and survey data. Paired t-tests and correlations compared environments overall and by distance between locations. Cross-classified multi-level models estimated associations with BMI.
Home neighborhoods had more favorable social environments while workplaces had more favorable SES and physical environments. Workplace and home measures were correlated (0.39–0.70) and differences between home and workplaces were larger as distance increased. Associations between BMI and neighborhood SES and recreational facilities were stronger for home environment (P≤0.05) but did not significantly differ for healthy food, safety, or social cohesion. Healthy food availability at home and work appeared to act synergistically (interaction P=0.01).
Consideration of workplace environment may enhance our understanding of how place affects BMI.
PMCID: PMC3779875  PMID: 23868527
Neighborhood; Body Mass Index
17.  Filling the Gaps: Spatial Interpolation of Residential Survey Data in the Estimation of Neighborhood Characteristics 
Epidemiology (Cambridge, Mass.)  2007;18(4):469-478.
The measurement of area-level attributes remains a major challenge in studies of neighborhood health effects. Even when neighborhood survey data are collected, they necessarily have incomplete spatial coverage. We investigated whether interpolation of neighborhood survey data was aided by information on spatial dependencies and supplementary data. Neighborhood “availability of healthy foods” was measured in a population-based survey of 5186 persons in Baltimore, New York, and Forsyth County (North Carolina). The following supplementary data were compiled from Census 2000 and InfoUSA, Inc.: distance to supermarkets, density of supermarkets and fruit and vegetable stores, housing density, distance to a high-income area, and percent of households that do not own a vehicle. We compared 4 interpolation models (ordinary least squares, residual kriging, spatial error regression, and thin-plate splines) using error statistics and Pearson correlation coefficients (r) from repeated replications of cross-validations. There was positive spatial autocorrelation in neighborhood availability of healthy foods (by site, Moran coefficient range = 0.10–0.28; all P < 0.0001). Prediction performances were generally similar for the evaluated models (r ≈ 0.35 for Baltimore and Forsyth; r ≈ 0.54 for New York). Supplementary data accounted for much of the spatial autocorrelation and, thus, spatial modeling was only advantageous when spatial correlation was at least moderate. A variety of interpolation techniques will likely need to be utilized in order to increase the data available for examining health effects of residential environments. The most appropriate method will vary depending on the construct of interest, availability of relevant supplementary data, and types of observed spatial patterns.
PMCID: PMC3772132  PMID: 17568220
18.  Socioeconomic Status and Tobacco Consumption Among Adolescents: A Multilevel Analysis of Argentina’s Global Youth Tobacco Survey 
Nicotine & Tobacco Research  2012;14(9):1092-1099.
The relationship between poverty and tobacco consumption among adolescents has not been extensively studied, and what evidence exists has come almost entirely from developed countries. Moreover, the impact of contextual factors—such as school-level poverty—remains unclear.
We obtained information about smoking behavior from the Global Youth Tobacco Survey in Argentina in 2007. School-level characteristics were derived by matching schools to census areas from the 2001 Census. Additional school-level information was obtained from the Ministry of Education. Random intercept models were used to evaluate the associations of school-level variables (poverty in the census area of the school, school receipt of social assistance, and public or private status) with current smoking, intention to quit, secondhand smoke exposure outside the home, support for smoke-free laws, purchase of single cigarettes among smokers, and susceptibility to smoking in 5 years among nonsmokers.
After controlling for age and sex, students attending schools receiving social assistance were more likely to smoke (odds ratio [OR] 1.35, 95% CI 1.02–1.80) and to purchase loose cigarettes (OR 1.66, 95% CI 1.08–2.54), whereas school poverty was significantly associated with secondhand smoke exposure (OR 1.27, 95% CI 1.04–1.58).
This study shows that an association exists between unfavorable contextual school characteristics and tobacco consumption and related measures among youth in Argentina. Efforts to prevent smoking may need to address the school-level factors that place youth at higher risk.
PMCID: PMC3529606  PMID: 22394595
19.  Exploring racial disparities in CHD mortality between blacks and whites across the United States: A geographically weighted regression approach 
Health & place  2012;18(5):1006-1014.
Coronary heart disease (CHD) mortality is one of the major contributors to racial disparities in health in the United States (US). We examined spatial heterogeneity in black–white differences in CHD mortality across the US and assessed the contributions of poverty and segregation. We used county-level, age-adjusted CHD mortality rates for blacks and whites in the continental US between 1996 and 2006. Geographically weighted regression was employed to assess spatial heterogeneity. There was significant spatial heterogeneity in black–white differences in CHD mortality (median black–white difference 17.7 per 100,000, 25th–75th percentile (IQR): 4.0, 34.0, P value for spatial non-stationarity < 0.0001) before controlling for poverty and segregation. This heterogeneity was no longer present after accounting for county differences in race-specific poverty and segregation and interactions of these variables with race (median black–white difference −13.5 per 100,000, IQR: −41.3, 15.7, P value for spatial non-stationarity = 0.4346). The results demonstrate the importance of spatial heterogeneity in understanding and eliminating racial disparities in CHD mortality. Additional research to identify the individual and contextual factors that explain the local variations in racial disparities is warranted.
PMCID: PMC3693935  PMID: 22835483
Racial disparities; CHD mortality; Poverty; Segregation; Spatial heterogeneity; Geographically weighted regression; United States
20.  Conceptual Approaches to the Study of Health Disparities 
Scientific and policy interest in health disparities, defined as systematic, plausibly avoidable health differences adversely affecting socially disadvantaged groups, has increased markedly over the past few decades. Like other research, research in health disparities is strongly influenced by the underlying conceptual model of the hypothetical causes of disparities. Conceptual models are important and a major source of debate because multiple types of factors and processes may be involved in generating disparities, because different disciplines emphasize different types of factors, and because the conceptual model often drives what is studied, how results are interpreted, and which interventions are identified as most promising. This article reviews common conceptual approaches to health disparities including the genetic model, the fundamental cause model, the pathways model, and the interaction model. Strengths and limitations of the approaches are highlighted. The article concludes by outlining key elements and implications of an integrative systems-based conceptual model.
PMCID: PMC3740124  PMID: 22224879
health inequalities; social determinants; systems
21.  Cumulative biological risk is socially patterned by education and income among African Americans in the Jackson Heart Study 
American Journal of Public Health  2012;102(7):1362-1369.
The purpose of this study was to examine the social patterning of cumulative dysregulation of multiple systems, or allostatic load (AL), among African Americans adults.
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 4,048 Jackson Heart Study participants.
Lower education and income were associated with higher AL scores in African American women and men. 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 AL score and the metabolic and immune domains persisted after adjustment for behavioral factors and were stronger for income than 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 no associations were observed for the metabolic component.
Findings support the hypothesis that AL is socially patterned by SES in African American women, but less consistently in African American men.
PMCID: PMC3371088  PMID: 22594727
22.  Walking Distance by Trip Purpose and Population Subgroups 
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.
This study examines the prevalence of walking and distances and durations of walking trips for different purposes among U.S. residents.
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.
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, 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.
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.
PMCID: PMC3377942  PMID: 22704740
23.  Using an agent-based model to simulate children’s active travel to school 
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.
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.
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.
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.
PMCID: PMC3668894  PMID: 23705953
24.  Reducing Violence by Transforming Neighborhoods: A Natural Experiment in Medellín, Colombia 
American Journal of Epidemiology  2012;175(10):1045-1053.
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.
PMCID: PMC3353133  PMID: 22472117
causality; economic development; environment; neighborhood; residence characteristics; violence
25.  Measuring Availability of Healthy Foods: Agreement Between Directly Measured and Self-reported Data 
American Journal of Epidemiology  2012;175(10):1037-1044.
A major challenge in studies of the impact of the local food environment is the accuracy of measures of healthy food access. The authors assessed agreement between self-reported and directly measured availability of healthful choices within neighborhood food stores and examined the validity of reported availability using directly measured availability as a “gold standard.” Reported availability was measured via a phone survey of 1,170 adults in Baltimore, Maryland, in 2004. Directly measured availability was assessed in 226 food stores in 2006 using a modified Nutrition Environment Measures Survey in Stores (NEMS-S). Whites, college-educated individuals, and higher income households (≥$50,000) had significantly higher reported and directly measured availability than did blacks, those with less education, and lower income households. Persons in areas with above average directly measured availability reported above average availability 70%–80% of the time (sensitivity = 79.6% for all stores within 1 mile (1.6 km) of participants’ homes and 69.6% for the store with the highest availability within 1 mile). Those with below average directly measured availability reported low availability only half the time. With revisions to improve specificity, self-reported measures can be reasonable indicators of healthy food availability and provide feasible proxy measures of directly assessed availability.
PMCID: PMC3353136  PMID: 22273535
food; reproducibility of results; residence characteristics; self report; validity (epidemiology)

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