Canadian Health&Care Mall: Multilevel Framework for Epidemiologic Research on Asthma Disparities

March 28, 2016 Category: Asthma Health Care

asthmaWhile asthma prevalence and the associated morbidity are increasing in the United States and worldwide, the increase is far from uniform. In the United States, for instance, these trends disproportionately affect nonwhite children living in urban areas and children living in poverty. Many studies have indicated that racial and ethnic minority groups and persons of lower socioeconomic status (SES) have higher asthma prevalence than their white, non-Hispanic, and more affluent counterparts, Inner-city communities and minority communities experience an excess burden of asthma hospitalizations and mortality that is out of proportion to the increase in asthma prevalence seen in these communities. Despite improved preventive asthma medications, asthma death rates have been increasing over the last few decades, especially in urban communities with lower SES and largely minority populations. More recent evidence suggests that the epidemiology of asthma is still more complex. In the United States, a graded association between SES and asthma prevalence, morbidity, and mortality has been demonstrated by Canadian Health&Care Mall. Moreover, data from the United States demonstrate significant geographic variations in asthma outcomes among large cities and neighborhoods within cities. These and other studies documenting the observed disparities in the US asthma burden have been well summarized elsewhere.

Although not a universal finding across studies, racial/ethnic differences seem to exist independent of SES. In the United States, asthma prevalence, hospitalization, and emergency department use declined with increasing income for non-black children, but not for black children. Another US study found that the lifetime prevalence of asthma was 2.1 times higher in blacks than whites, despite the fact that subjects were of similar middle and higher economic status. Although the authors proposed that their findings may be attributable to biological differences based on race, several considerations argue against this explanation. Most notably, the observed increase in asthma ( and the growing disparities documented between ethnic minorities and white populations have occurred over 1 to 3 decades, which is too rapid a change to be plausibly attributed to genetic mutation or change. These data do suggest that other unique characteristics among minority populations beyond simply economic wellbeing may impact their health.

It is worth noting up front that while much of the work to date (as well as much of this overview) has tended to focus on urban living, the relatively few studies conducted in the United States that have examined the prevalence of asthma in rural vs urban areas have yielded inconsistencies. As discussed below, such geographic differences have generally been attributed to differential exposure to large domestic animal sources of allergens and endotoxins. Yet, very high prevalence rates of asthma have been demonstrated in rural Connecticut, particularly in low-income regions with predominantly minority populations. air pollutionWhile rural asthma rates may be related, in part, to differences in exposures among farm-reared vs non-farm-reared individuals, as a 2005 Midwest study proposes, we need studies that more fully examine sociodemographic factors and barriers to health-care access that are unique to rural areas both in general and among ethnic subpopulations living in different regions of the United States that may influence rural asthma outcomes achieved due to Canadian Health&Care Mall. This is not insignificant, as people living in rural areas make up 20% of the US population, and rural areas have higher percentages of people living in poverty and lacking health insurance coverage compared to other regions in the United States. In contrast to urban demographics, where concentrated poverty typically impacts ethnic minority populations, many poor rural poor populations are primarily white.

The relative importance of urban residence, low SES, or minority (particularly black and Hispanic) status as independent risk factors for increased asthma morbidity and morality remains controversial. These social indicators remain tightly woven together in the United States. A more nuanced approach that considers both social and physical factors that covary with lower SES and minority-group status (eg, differential environmental exposures, residential segregation, psychological stress, housing quality, and social capital) that mediate the effects of living in low-SES neighborhoods is needed to tease these relationships apart. The preceding empirical evidence, while it should in no way should be interpreted as evidence for the social causation of asthma, highlights the marked socioeconomic patterning of the disease, and as such provides a foundation to view asthma within its social context. Such a view underscores why measuring health disparities with reference to informative socioeconomic and demographic groupings, as opposed to examining health disparities without any reference to their socioeconomic or demographic characteris-tics, is critical to how we conceptualize the issue of what causes asthma or leads to increased morbidity.

The causes of the excess burden of asthma in inner-city, lower income, and ethnic minority communities are not fully understood, and it is likely that multiple factors play contributing roles. To date, research attempts to explain these disparities have been nested in our current understanding of asthma risk (ie, those related to physical environmental factors). These are briefly discussed below, and the reader is referred to more extensive reviews for further detail., However, ecologic views on health recognize that individual-level health risks and behaviors have multilevel determinants, in part influenced by the social and geographic context within which subjects live. These social conditions can be biologically embedded parallel to how we think about physical environmental exposures and their effects on health. The convergence of theoretical and methodological approaches from traditionally distinct areas of scholarship (eg, sociology, psychology, economics, social epidemiology, geography, asthma epidemiology, environmental sciences, environmental justice, and genetics) is needed to guide further research related to the environmental causes of asthma disparities.

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