Whether first and second generation Mexican-Americans were compared using the cross-survey approach (HHANES first generation versus NHANES 1999–2004 second generation) or the within-survey approach (HHANES first versus second generation and NHANES 1999–2004 first versus second generation), significant generational differences in individual cardiovascular disease risk factors levels were found. Specifically, second generation men had a higher rate of hypertension than first generation men in the cross-survey comparison and in both within-survey comparisons; second generation women had a higher hypertension rate than first generation women, but only in the cross-survey comparison; second generation men and women had lower smoking rates in the cross-survey comparisons and in men, in the within-survey comparison using HHANES only; second generation men had a lower mean HDL cholesterol level in the cross-survey comparison whereas second generation women had a higher mean HDL level in the cross-survey comparison and both within-survey comparisons; and lastly, second generation women had a lower mean total cholesterol level in the cross-survey comparison.
As discussed in the Introduction, most previous studies of generational differences in cardiovascular disease risk factors in Hispanics relied on cross-sectional (within-survey) comparisons. However, generational differences found in cross-sectional data may be confounded by secular trends in the health of immigrants. The optimal way to investigate generational differences in risk factor levels would be to use multigenerational longitudinal data that includes immigrants and their children. Unfortunately, these kinds of longitudinal studies of Mexican immigrants and their children are not currently available. In this study, we have addressed this issue by comparing first generation adults in an older data set (HHANES) with second generation adults in a newer data set (NHANES), approximating comparisons between immigrant parents and their US-born children (i.e., cross-survey approach). In the social sciences, the technique of approximating longitudinal data by using multiple waves of cross-sectional data is referred to as the pseudo-cohort approach [22
]. Our results suggest that indeed there are important differences between the results obtained from cross-survey (cross-survey) and cross-sectional (within-survey) comparisons; in the case of this study, particularly among women. Specifically, first and second generation women differed with respect to total cholesterol, hypertension and smoking in the cross-survey comparisons but not cross-sectional comparisons. Researchers using cross-sectional data to investigate generational differences in health should be aware of the potential for confounding due to secular trends in the health of immigrants and seek to check their results using pseudo-cohorts when feasible.
Despite there being differences in individual risk factor levels, first and second generation Mexican-Americans had similar overall risks of developing coronary heart disease over a ten-year time horizon. Specifically, first and second generation men and women had statistically similar 10-year risk of coronary heart disease as estimated by the FRS, whether immigrant men and women were compared with their second generation counterparts using cross-survey or within-survey comparisons. These results suggest that the risk factor distributions favoring one generation may have been balanced by those favoring the other, resulting in no net difference in near-term cardiovascular risk. For example, compared to first generation women, second generation women had higher hypertension rates but also lower smoking rate rates. Another possible explanation for the lack of any significant generational differences in the FRS may have been the small numbers of older first and second generation Mexican-Americans in HHANES. In HHANES, there were only 61 men and 75 women that were 65 years of age and older. Had there been greater numbers of older Mexican-American men and women in these studies, significant generational differences in risk might have been detectable.
In contrast to this study, previous studies have found that less acculturated Hispanics have more favorable cardiovascular disease risk factor profiles than more acculturated Hispanics. For example, compared with US-born Hispanics, foreign-born Hispanics have been found to have more favorable levels of blood pressure, cholesterol, diabetes, body mass index, abdominal circumference, smoking, and coronary calcifications [6
]. There are, however, important methodological differences between this and previous studies. First, previous studies have frequently compared foreign-born Hispanics to US-born Hispanics, not distinguishing among the multiple generations of US-born Hispanics. If acculturation continues across multiple generations as suggested by Portes and Rumbaut [29
], then important differences between second, third, fourth, and higher generations of Mexican-Americans may be unaccounted for in earlier studies. In contrast, this study was limited to comparisons between first and second generation individuals. Second, many previous studies pool Hispanics together regardless of ethnic or national background. There is, however, mounting evidence that Hispanic subgroups differ with respect to risk factors, mortality and many other important measures of health status [30
]. To avoid the possible confounding of generational differences by compositional differences in national origin, this study is limited to Mexican-Americans. Finally, generational status is not a measure for acculturation, though the two measures are correlated. Generational status is solely determined by the birthplaces of an individual and of her parents. By contrast, acculturation is a multi-dimensional construct that is defined by factors such as engaging in culturally-specific behaviors (e.g., food, music and media); language proficiency; knowledge of culture-specific history and current events; the cultural makeup of one’s social network; and one’s own ethnic and cultural identity [31
]. Thus studies that have used measures of acculturation may not find the same results as this study that used generation.
Access to care could have confounded the results of this study, particularly with respect to cholesterol levels. Conceptually, access to care might influence cholesterol levels by leading to the receipt of cholesterol lowering drugs. Thus individuals with better access to care might have lower cholesterol levels independent of their generational status. Unfortunately, HHANES does not include variables that allow us to evaluate the prevalence of dyslipidemias (as opposed to cholesterol level). To better understand the relationship between cholesterol levels and access to care, we regressed cholesterol on generational status, age, and usual source of care (yes/no). Among women, controlling for usual source of care made no difference in the results. Among men, however, controlling for usual source of care resulted in the contrast between first and second generation within HHANES becoming insignificant. Interestingly, men with a usual source of care had higher cholesterol levels (beta = 6.02; P = 0.05) than men without a usual source of care, suggesting that need for care (as measured by cholesterol) was associated with access to care (as measured by usual source of care). The impact of the risk factors in this study on future cardiovascular morbidity and mortality will depend upon access to health care and to appropriate risk reducing therapies.
Mexican-Americans are the largest and fastest growing subgroup of Hispanics in the US, yet despite their demographic importance Mexican-American immigrants and their children remain vastly understudied groups. Because of their increasing numbers, Mexican-American immigrants and their children are destined to have significant impacts on the US health care system. Therefore gaining a better understanding of generational changes in health and factors that influence generational changes in health among Mexican-Americans is essential. This research study takes a small step towards developing a better understanding of the role of generational change and health. However, much more population-based research targeting Mexican-American immigrants is needed before effective interventions to maintain and improve health in these groups can be developed.