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RESEARCH |
At the time of the study, both authors were with the Office of Social Environment and Health Research, Department of Community Medicine, West Virginia University, Morgantown.
Correspondence: Requests for reprints should be sent to Elizabeth Barnett, PhD, MSPH, Office of Social Environment and Health Research, Department of Epidemiology and Biostatistics, University of Florida College of Public Health, 13201 Bruce B. Downs Blvd, MDC 56, Tampa, FL 33612-3805 (e-mail: ebarnett{at}hsc.usf.edu).
| ABSTRACT |
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Objectives. This study analyzed coronary heart disease (CHD) mortality trends from 1985 to 1995, by race and sex, among Black and White adults 35 years and older to determine whether adverse trends were evident in any US localities.
Methods. Log-linear regression models of annual age-adjusted death rates provided a quantitative measure of local mortality trends.
Results. Increasing trends in CHD mortality were observed in 11 of 174 labor market areas for Black women, 23 of 175 areas for Black men, 10 of 394 areas for White women, and 4 of 394 areas for White men. Nationwide, adverse trends affected 1.7% of Black women, 8.0% of Black men, 1.1% of White women, and 0.3% of White men.
Conclusions. From 1985 to 1995, moderate to strong local increases in CHD mortality were observed, predominantly in the southern United States. Black men evidenced the most unfavorable trends and were 25 times as likely as White men to be part of a local population experiencing increases in coronary heart disease mortality.
| INTRODUCTION |
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Geographic variations in CHD death rates within the United States have been observed for decades.7,925 An excess of CHD mortality in the southern United States was first observed in 1950,11 and it appears to have persisted over time.9,10,12,15,22 In the Atlas of United States Mortality, maps of smoothed (estimated) heart disease mortality rates for 1988 to 1992 showed a clear southern excess among Blacks and Whites of both sexes.22 Several studies have described geographic disparities in CHD mortality based on state of residence,7,14,24 ruralityurbanicity,911,13,18,19,21,25 local educational achievement profiles,20 and community occupational structure.16,23,26
Concomitant with observations of geographic variation in level of CHD mortality, substantial spatial variations in CHD temporal trends have been reported.7,9,10,15,18,25,27,28 Although CHD mortality rates began declining nationally in the mid-1960s, there were substantial local variations in the timing of the onset of decline for Whites, with many local areas not experiencing declining mortality until the early to mid-1970s.27,28 Late onset of decline in CHD mortality among Whites was associated with rurality and more adverse community occupational, educational, and income profiles.28,29 A study of geographic variation in CHD mortality trends among Whites for the period 1968 to 1978 showed the slowest rates of decline in Appalachia and the mid-South for men and in parts of Texas, the Mississippi River Valley, and Appalachia for women.15
More recently, consistently slower rates of decline have been observed for both African Americans and Whites in rural areas, particularly in the South21,25 and in Appalachia.9,10 One study produced evidence of adverse (i.e., increasing) trends in CHD mortality from 1984 to 1995 among African American men of lower social class residing in North Carolina.30 In Appalachia, elderly Black men residing in rural areas experienced no decline in CHD mortality between 1980 and 1993.9,31
In this article, we report geographic patterns of CHD mortality among United States adults for the period 1985 to 1995. This study was part of a larger project focused on ruralurban disparities in heart disease, with an emphasis on identifying characteristics of the social environments of local areas that affect the prevalence of risk factors and trends in mortality. The geographic unit of analysis for this study was the labor market area (described subsequently).32 Given evidence from several studies of slowing declines among some demographic groups and adverse trends in localized populations of Black men, we were particularly interested in determining whether the much-acclaimed 25-year decline in CHD mortality was still apparent for adults in all localities of the United States.
| METHODS |
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Labor Market Areas
As mentioned, the geographic unit of analysis in this study was the labor market area. Labor market areas consist of 1 or more counties and define small regions in which participants in local labor markets both live and work; that is, they encompass the space in which labor market processes are grounded.32,3437 Given our interest in the influence of the social environment, particularly economic development, on geographic patterns of CHD mortality, labor market areas offered a more theoretically defensible approximation of "communities" than counties or other county aggregates. Labor market areas are relatively large in land area relative to the small areas defined for other types of epidemiologic studies, such as analyses of cancer clusters. Consequently, each labor market area contains a heterogeneity of microenvironments, including neighborhoods and households. However, areas as small as neighborhoods, often defined according to census block groups, are inappropriate for studies of economic development and labor market processes, because these processes operate on a larger spatial scale.
The delineation of labor market areas used in this study was based on extensive analysis of empirical journey-to-work and residence data for counties, county equivalents, and the District of Columbia obtained from the US census.37 There are 394 labor market areas defined for the United States. These areas cross state boundaries, which is appropriate given the nature of local labor markets. Each labor market area comprised at least 100 000 inhabitants in 1990, and hence the land areas of labor market areas tend to be larger in the western United States, which is more sparsely populated. The largest city or town within a labor market area is typically used in describing the area; we follow that convention here.
Analysis
We obtained death certificate computer files from the National Center for Health Statistics. Deaths from CHD were defined for this study on the basis of underlying cause of death. Specifically, we included underlying cause-of-death codes 402 (hypertensive heart disease), 410 to 414 (ischemic heart disease), and 429.2 (cardiovascular disease, unspecified) as defined in the International Classification of Diseases, Ninth Revision. This method was used in previous studies and has been recommended by several researchers.6,18,23 For each decedent, we abstracted data on age, race, sex, year of death, and county of residence. US Bureau of the Census intercensal population estimates were used to provide race-, sex-, and age-specific population counts for all counties for the years 1985 to 1995.
County-specific CHD deaths and population counts were summed to the labor market area level by year of death, sex, race, and 10-year age group. Age-specific death rates were computed and used to calculate, by race and sex, age-adjusted annual CHD mortality rates for each labor market area. The 1970 US population, the standard currently used by the Centers for Disease Control and Prevention, was used as the standard for age adjustment. Following the convention of the National Center for Health Statistics,38 we calculated race- and sex-specific CHD death rates only for those labor market areas in which the population experienced an average of at least 20 CHD deaths per year.
In the case of White men and women, rates were calculated for all 394 labor market areas in the United States. However, solely as a result of the underlying geographic distribution of the Black population in the United States, CHD death rates were calculated for only 175 labor market areas in the case of Black men and only 174 areas in the case of Black women. These labor market areas constituted more than 95% of the total African American population in the United States during the study period.
To quantify CHD mortality trends over the study period, we fit separate linear regression models to the log-transformed, age-adjusted rates for each racesex group in each labor market area. Specifically, we used the following model: y =
+ ß(x) + e, where y is ln(age-adjusted rate), x is year, and e is the error term. The average annual percentage change in mortality is 100(eß 1). The use of a log-linear model allowed us to compare relative changes in mortality over time for populations with markedly disparate absolute CHD death rates. In addition, linear regression of the log-transformed rates assumed constant proportional change over time, as opposed to constant absolute change over time. This has been shown to be a more appropriate model for examining temporal trends in mortality.39 We used the standard errors from the regression models in calculating confidence intervals for average annual percentage change values.
Maps for each racesex group were created on the basis of the regression estimates of average annual percentage changes in CHD death rates from 1985 to 1995. The following 5 categories of trend outcomes were mapped for each racesex group, permitting comparisons across the maps: strong decline (5% or greater decline in mortality each year), moderate decline (1% to 5% decline in mortality each year), negligible change (less than 1% decline or less than 1% increase per year), moderate increase (1% to 5% increase in mortality each year), and strong increase (5% or greater increase in mortality each year). We took a conservative approach in categorizing local trends, considering a labor market area to have experienced an increasing trend only if death rates increased at least 1% per year. Each map shows all of the labor market areas in the United States, shaded to reflect the appropriate trend category. Overall, darker shades represent adverse trends, and lighter shades represent favorable trends. Labor market areas for which there were insufficient data to calculate CHD death rates are unshaded on the maps for Black men and Black women.
| RESULTS |
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| DISCUSSION |
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Our results are consistent with previous reports of widening geographic inequalities in CHD mortality nationwide,17 unfavorable patterns of CHD mortality in the South,1012,15,22,25,28 and recent adverse trends in CHD mortality among African American men.9,30 Whereas Black women were about 1.5 times more likely than White women to experience adverse CHD mortality trends, Black men were more than 25 times as likely as White men to experience adverse CHD mortality trends from 1985 to 1995. In addition, a substantial minority of African American adults (9.3% of men and 29.3% of women) experienced negligible changes in CHD mortality over the study period.
Geographic disparities in health outcomes may be attributed to either compositional or contextual effects.42,43 Composition refers to the individual characteristics of people who live in a local area (e.g., socioeconomic status, prevalence of behavioral or physiologic risk factors), while context refers to characteristics of local social environments that are not reducible to individual traits (e.g., labor market structure, tax base, income inequality). Several recent studies have shown that community context affects health outcomes above and beyond the impact of compositional effects.4247 Ameliorating the adverse trends reported here for localities across the country will first require an understanding of the relative effects of individual traits and social environmental contexts in producing population patterns of CHD.
| Acknowledgments |
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| Footnotes |
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Accepted for publication October 20, 2000.
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