This study examined the contributions of individual characteristics and NSES to racial/ethnic differences in 5 health behaviors—fruit and vegetable intake, sedentary lifestyle, percentage of calories from fat, tobacco use, and binge drinking—among Whites, Mexican-Americans and Blacks in the United States. Our analyses build on prior studies that have found associations of age, gender, educational attainment, and income with health behaviors,2,5,24,25
as well as on recent research published in this journal (American Journal of Health Behavior
) showing that neighborhood deprivation increases the risk of smoking, sedentary behavior, fat intake, and binge drinking.8
However, our study advances the research on disparities in health behaviors by conducting a Oaxaca decomposition analysis, which enables us to assess the degree to which racial/ethnic differences may result from differential group responses to measured characteristics. To our knowledge, decomposition analysis has not previously been applied to study disparities in health behaviors.
Consistent with earlier research, we found that individual demographic and socioeconomic factors and NSES had strong independent associations with health behaviors. For each behavior, however, effect sizes varied by race/ethnicity, often substantially, suggesting the potential utility of a decomposition analysis. Indeed, our decomposition analyses found that the contribution to disparities of racial/ethnic differences in the effects of measured characteristics was sometimes larger than the contribution of group differences in these characteristics. Our analysis of smoking prevalence in Whites and Mexican Americans provides a particularly striking example of the importance of group differences in the effects of measured characteristics. Thus we found that, whereas Whites’ and Mexican Americans’ individual characteristics and NSES would predict a lower smoking prevalence among whites, in fact Mexican Americans had lower a lower prevalence of smoking.
Differential effects of individual characteristics and NSES may result from omitted dimensions of variables that we otherwise included in our analyses. For example, our measures of individual socioeconomic status did not capture educational quality or wealth. Differential effects may also be due to individual factors that we were forced to omit from our analyses altogether, due of lack of data, such as attitudes and preferences, culture and degree of acculturation, and experience of discrimination. In a related vein, our measure of NSES is a proxy measure that stands in for differences across neighborhoods in access to facilities for recreation and exercise, crime, availability of different types of food, quality of public services, and other factors. The range of possible explanations for differential responses makes it difficult to identify with certainty a specific cause for any particular health behavior. Nonetheless, with this caveat in mind, several observations regarding our findings merit discussion.
In comparing Whites’ and Mexican Americans’ health behaviors, we found that differential responses to individual characteristics and NSES made the dominant contribution to the gap in 4 behaviors: calories from fat, tobacco use, and binge drinking in both genders. These findings are consistent with a major role of cultural differences in the differential responses. Previous studies have documented the importance of differences in dietary practices between Whites and recent Mexican immigrants,26,27
with the latter generally having healthier diets that are lower in fat.26,27
Studies have also shown that acculturation to U.S. culture is associated with unfavorable dietary changes among Mexican-Americans.26–28
Our findings suggest that, in the case of dietary fat, the effects of culture may dominate other factors.
Tobacco use and alcohol consumption are also culturally embedded behaviors. Our findings for tobacco use are especially noteworthy, since the large contribution of differential responses reversed the direction of the gap between Whites and Mexican Americans that would have been predicted based only on their individual characteristics and NSES. In fact, prior studies have found that Mexican immigrants have low rates of smoking rates, and that smoking rates increase with acculturation.29,30
Notably, people who self-identity as Mexican American are more likely to smoke than those who self-identify as Mexican.29
Other studies have demonstrated higher smoking rates in second generation and/or those who are U.S. born compared with immigrants.31,32
Our findings for binge drinking are even more striking, as we found that the sizeable contributions from differential responses to individual characteristics and NSES were opposite in direction for men and women. Thus Mexican-American men engaged in binge drinking much more frequently than would have been predicted based on their individual characteristics and NSES, whereas Mexican-American women engaged in binge drinking much less often than would have been predicted. This finding is consistent with previous research suggesting that Hispanics (although not a homogeneous population) demonstrate more conservative views of alcohol use than Whites;33,34
these conservative attitudes are especially likely to influence the drinking behavior of women.34
Our findings suggest that, as with dietary fat, the effects of culture on tobacco and alcohol use may be the main reason for differential responses to individual characteristics and NSES between Whites and Mexican Americans.
In comparing Whites’ and Blacks’ health behaviors, differential responses to individual factors and NSES made the dominant contribution to the gaps in only 2 behaviors: calories from fat and binge drinking among women. Specifically, Blacks consumed a higher percentage of calories from fat in their diets than would have been predicted based on their individual characteristics and NSES. Blacks have different dietary traditions than Whites,35,36
and these traditions include several foods that are high in fat.37–40
Conversely, Black women engaged in binge drinking much less often than would be predicted. Studies also suggest that, as in the case of Mexican Americans, Blacks have more conservative views toward alcohol than do Whites.41
These conservative views may disproportionally affect women. Gender roles tend to vary by ethnicity and culture and these variations can affect the health status of Blacks in the U.S.42,43
Research has pointed to the role of religiosity in decreasing risk of binge drinking, and thus compiled with research that has shown women to be consistently more religious than men,44
this could be one explanation of lower binge drinking than one may have predicted given individual-level characteristics and NSES alone. Among men, we observed higher binge drinking from African American men compared with White men. Other45
research has shown that Black neighborhoods have more outdoor advertising space than White neighborhoods, and these spaces disproportionately market alcohol and tobacco advertisements.46,47
This may impact African American men differently than African American women, given literature which has shown differential responses by gender. Jackson48
notes an inverse association between income and hypertension for African-American women and contrasts this with African-American men.49
Further, Diez-Roux et al49
reported that African-American men in Harlem with a college degree had higher levels of hypertension when compared to those with only a high school education. Still, other studies have shown that substance use may be an unhealthy coping response to perceived unfair treatment for some individuals.50,51
Naturally, additional unmeasured factors, mentioned earlier, are also likely to influence the differential responses to individual characteristics and NSES across racial and ethnic groups, and quantifying the role of each unmeasured factor is not possible. Consequently, our discussion in the preceding paragraphs must remain speculative. Nonetheless, the observation that, on the whole, differential responses made larger contributions to the gaps in health behaviors between Mexican Americans and Whites than to the gaps between Blacks and Whites offers additional indirect support for the notion that culture may be the major driver of the differential responses between Mexican Americans and Whites. Despite their different histories and traditions, Whites and Blacks in the U.S. share a common culture to a much greater degree than Whites and either Mexican immigrants or less acculturated Mexican Americans do.
Several limitations of our study deserve mention. First, because the NHANES III data are cross-sectional, we were unable to examine the temporal associations among individual characteristics, NSES, and health behaviors. Second, because of the high degree of racial residential segregation in the U.S., Blacks and Hispanics are far more likely than Whites to be poor and to live in poor communities.52
Thus it may be difficult to eliminate completely the confounding between individual socioeconomic status and NSES in the decomposition analyses. Nonetheless, in our data we found sufficient variation to obtain relatively precise estimates of both individual and neighborhood effects. Third, although NHANES III collects data on a large and representative national sample, rural populations are underrepresented in our study and, consequently, our findings are not generalizable to rural populations. Next, all data is based on self-report and we do not know whether there were differences in reporting bias either by behavior, or related to other characteristics. In a review of the literature, we found very limited evidence to suggest that social desirability response bias was likely to have had a major effect on our findings, though we cannot be sure.53–55
Last, NSES is a very useful, though non-specific, measure of neighborhood resources.20
Ideally, we would have detailed data on resources such as parks, recreational facilities, different types of food outlets, crime, and public services, but these data were unavailable.
These limitations notwithstanding, our study underscores the fact that solutions to health disparities are complex, and that policymakers must account for a wide range of factors in designing policies. More specifically, our findings imply that even if social policy were able to equalize socioeconomic characteristics across racial/ethnic groups, we would probably continue to observe differences in health behaviors. Readily measurable characteristics are often the focus of policy recommendations in studies of health disparities (e.g., income transfers, educational interventions, or neighborhood improvements), but little if any attention has been given to the fact that reducing socioeconomic inequality may not eliminate disparities if there are differential responses to key individual and neighborhoods factors. Understanding the mechanisms for differential responses could inform community interventions and public health campaigns that aim to target particular groups, although dealing with this source of disparities is likely to remain a challenge.
Our findings also suggest a need for more qualitative research that examines the underlying mechanisms for racial/ethnic differences in responses to individual sociodemographic characteristics and NSES. Understanding these mechanisms and the unmeasured factors that might matter is critical for developing successful approaches to reducing disparities in health behaviors. Our study also supports the notion that our current measures that capture socioeconomic influences on health are inadequate. Braveman and colleagues56,57
have stressed the multidimensional nature of socioeconomic status, and the fact that it can change over the life course. The need for additional work on measure development applies to both the individual and neighborhood levels.