From the Population Research Center, Department of Sociology, The University of Texas, Austin, TX.
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ABSTRACT |
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acculturation; Asian Americans; bed rest; disability evaluation; emigration and immigration; health status; health surveys; National Center for Health Statistics (U.S.)
Abbreviations: NHIS, National Health Interview Survey; OR, odds ratio
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INTRODUCTION |
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Unfortunately, studies of the health of Asian and Pacific Islander immigrants based on nationally representative data are rare. Compared with other US minorities, there has generally been little research on the Asian and Pacific Islander population, which has been described as "one of the most poorly understood minorities [whose] health problems and health care needs have not been adequately recognized or addressed" (12, p. 26; 13
). Furthermore, because of a lack of data sets large enough to enable intraethnic distinctions to be made in multivariate analyses, most previous research has analyzed the Asian and Pacific Islander population as an undifferentiated whole, masking the high degree of heterogeneity known (or suspected) to exist across national origin groups with respect to socioeconomic status, immigrant status, health status, and cultural characteristics (14
, 15
).
The feasibility of studying the health of specific Asian and Pacific Islander groups has been enhanced materially, because data generated by the National Health Interview Survey (NHIS) from 1992 onward recently became available for research. An Advance Data report (3) based on these new data (pooled for 19921994) appeared in a 1998 publication of the US Department of Health and Human Services; these data indicated that Asian and Pacific Islander subpopulations are dissimilar with respect to health conditions as well as socioeconomic and demographic characteristics. However, the purpose of advance reports is to provide timely descriptions, not to model outcomes. A later study, which pooled 19861994 NHIS data but did not analyze specific Asian and Pacific Islander groups, indicated that the Asian and Pacific Islander population as a whole was very similar to Whites with regard to the sex-specific and age-adjusted percentages in poor or fair health (16
). Neither of these highly informative studies investigated the impact of immigration on health.
The great diversity within the Asian and Pacific Islander population is associated with two different immigrant streams. The first is from countries that already have relatively large populations in the United States, for example, Chinese, Filipinos, Japanese, Koreans, and, increasingly, Asian Indians, who tend on average to be highly educated and skilled (even when compared with the White majority) (17). The second stream consists of lower-socioeconomic- status groups and includes large numbers of refugees from Southeast Asian countries such as Vietnam (4
). Asians and Pacific Islanders in the former group seem to be healthier on average than those in the latter group (3
), and important differences within as well as between these two migration streams are almost certain to exist. It is quite likely then that immigrant status (both whether persons are foreign born or US born (nativity) and time spent in the United States since immigration (duration)) is crucial to understanding health variations in the Asian and Pacific Islander population.
Prior research suggests two explanations for the health and mortality advantages of foreign-born persons: positive selection of immigrants and cultural "buffering." The first explanation hypothesizes that migration is selective of healthier and more-robust persons (9, 18
). The second suggests that, compared with the United States, other cultures (at least Hispanic cultures) are more likely to be characterized by norms and values proscribing risky behaviors (e.g., smoking, abuse of alcohol or drugs) and promoting healthy behaviors, including stronger familial and social support networks and better nutrition (7
, 8
, 19
, 20
). These hypotheses should be viewed as complementary rather than competing; that is, if positive selection does play a prominent role, immigrantsif all other relevant factors do not changeshould be healthier than the native born. In addition, if the cultural interpretation is also valid, not only would immigrants be healthier but their advantage would also erode over time as acculturation to US society proceeded. In other words, the validity and complementarity of the two propositions would be supported by the observation that immigrants are healthier than their US-born counterparts and that, among immigrants, there is a gradient such that health declines with duration in the country (21
). To test the two hypotheses, the number of years an immigrant has been in the United States must be included in analytical models.
Accordingly, the primary objective of our research was to examine the effect of immigrant status (both nativity and duration) on the health of Asians and Pacific Islanders by constructing models in which national origin was a covariate. This examination enabled us to test the two hypotheses and to provide, to our knowledge, the first assessment of immigrant status on variation in multiple indicators of health across specific Asian and Pacific Islander adult populations, taking into account the effects of immigrant status.
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MATERIALS AND METHODS |
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With the exception of family income, the amount of missing data for all variables included in this study was negligible. Income information was missing for about 17 percent of respondents. To evaluate the possibility of bias introduced by the missing income data, parallel regressions were performed in which income was first included and then excluded; the result was that no changes in our conclusions were required whether the cases for whom income was missing were included or not. Hence, following previous research, we included a missing category in the variable for operationalization of income (11, 25
). SUDAAN software was used to produce standard errors and confidence intervals appropriate to the survey design (26
).
We focused on the health of persons aged 25 years or older, which yielded a sample of 8,249 Asians and Pacific Islanders plus more than 208,000 Whites, with the latter included in the descriptive analysis only (for reasons mentioned below). Following presentation of descriptive results, the greatest attention was given to the relation between immigrant status and health indicators, adjusting for the effects of covariates shown or hypothesized to affect health status. Net effects were estimated by using logistic regression and were reported in the form of odds ratios; significance levels and confidence intervals were computed by using Wald statistics (). The White majority was not included in the regression models because of the likelihood that the much larger size of that group would overwhelm and obfuscate the associations involving Asians and Pacific Islanders. However, all multivariate models were reestimated with Whites first included in and then omitted from the regression analysis, and the general conclusions regarding the impact of immigrant status remained the same.
From 1992 through 1995, the NHIS enabled 10 specific Asian and Pacific Islander populations to be identified. In our study, we distinguished eight groups: Chinese, Filipino, Asian Indian, Japanese, Korean, Vietnamese, Pacific Islander, and Other Asians. It was possible to identify Hawaiians, Guamanians, and Samoans separately, but these groups taken separately represented too few cases for multivariate modeling and so were combined with other even-smaller Pacific Islander populations. Even so, the number of Pacific Islanders was so small that we could draw only tentative conclusions for that group. The "Other Asian" category is a residual that allows no further race/ethnic subdivisions. Refugee groups from Southeast Asia (e.g., Cambodia and Laos) make up a nonnegligible portion of this category.
The immigration variable was divided into four categories: native born; immigrant, duration 04 years; immigrant, duration 59 years; and immigrant, duration 10 years or more. This specification is similar to that used in the 1998 National Center for Health Statistics Advance Data report (3) as well as in other publications (e.g., (28
)). Most crucial perhaps is the 5-year duration cutpoint, because 5 years must elapse before an immigrant to the United States can obtain citizenship (spouses of citizens may become naturalized within 3 years). The Advance Data report also identified immigrants residing in the United States for less than 1 year and for more than 15 years. However, the small number of cases in the former category prevented its use in our multivariate analysis, and our ancillary research (not shown) made it clear that the effects associated with residence of 15 years or more were quite similar to those obtained when duration was top-coded at 10 years.
We focused on three health outcomes. The first was respondent-reported health assessment, for which the possible responses were poor, fair, good, very good, and excellent. Following recent research (16), we collapsed this measure into two categories: 1) poor and fair, and 2) good, very good, and excellent. Also of interest was whether the normal daily activities of adults are limited by disability, and we drew on the NHIS "activity limitation status" item to distinguish those persons with some activity limitation from those with no limitation. We also included information on the annual number of days spent in bed because of illness. Spending even 1 day in bed suggests an illness of at least modest severity, and being bedridden for a week or more would appear to indicate a more serious condition. All of the health items were based on self-reports, which have repeatedly been demonstrated to be both useful indicators of actual health status and predictors of mortality risk (16
, 29
, 30
).
We also examined the effects of Asian and Pacific Islander group membership and immigrant status on the annual number of visits to a physician and a measure of regular access to health care. Although the issue of access was not the primary focus of our research, for more than a decade there has been concern about whether the Asian and Pacific Islander population is inadequately served by the US health care system (12, 30
). Particularly relevant for our present purposes was the possibility that immigrants may be especially underserved (27
, 31
) and that duration of residence may affect immigrant access to medical care (27
, 28
). Providing a substantive interpretation of variation in physician visits is complicated, because this variable plausibly can be viewed as either a proxy measure of health status or an indicator of access to health care, or both. Physician visits were divided into three categories: none, one or two, and three or more. Many persons in excellent health may elect to have regular preventive examinations, but several visits to a physician in any one year could also indicate health problems. It might be reasonable to view three or more visits to a physician in a year as a marker for some degree of ill health, one or two visits as "normal access," and no visits as indicative of inadequate access. Unfortunately, the conceptual problem remains the same; that is, such an approach quickly leads to the confounding of health status with access to health care. Thus, we also included a direct indicator of access to health care (from data available in NHIS supplements for 19931995) that drew upon the item that inquired whether respondents had a usual person/place for medical care. Responses indicating one or more regular sources of care were coded "yes," those who reported no regular source were coded "no," and cases for whom data were missing were omitted. Health status was controlled in multivariate models when the effects of immigrant status on physician visits and regular source of medical care were estimated.
The associations of interest were adjusted by using a wide range of variables, including sex, age, marital status, living arrangement, family size, educational level, family income, and employment status, each of which has been demonstrated to have important effects on the health of adults or to be useful as a control when estimating the effects of other variables on health (4, 14
, 16
, 17
, 28
, 31
). As evident in the tables that follow, measurement of the control variables was conventional and straightforward.
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RESULTS |
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Over one fifth of Pacific Islanders reported a week or more spent in bed annually, a figure about eight percentage points higher than that for Whites, Asian Indians, and Vietnamese and approximately twice as high as the proportion for other Asian and Pacific Islander populations. Only 50.5 percent of Pacific Islanders had zero bed days; in other groups, the range was from about 57 percent (Japanese and Whites) to 68.3 percent (Chinese). The modal category for annual physician visits was three or more for Whites and for five of the Asian and Pacific Islander groups (around 40 percent for all six groups). For Japanese, Chinese, and Filipinos, one or two visits was the most frequent response. Only among Koreans was zero visits to a physician the mode. The Chinese and Koreans were least likely to have regular access to health care. Roughly three fourths of adults in these two groups reported a regular source of medical care as compared with 8090 percent for each of the other groups.
Cross-tabulations were constructed of health variables, by immigrant status, for the entire Asian and Pacific Islander population taken as a whole (not shown; data available from the authors upon request) because the conclusions from these cross-tabulations were identical to those that emerged from the unadjusted (baseline) models (tables 3 and 4). In any event, it was the net or adjusted associations that were of primary interest.
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Multivariate models of health status. Controlling for demographic and socioeconomic diversity, and including Asian and Pacific Islander subgroup membership as a covariate, resolved most of the ambiguity. Results from the fully adjusted model (bottom panel of table 3) showed that, compared with US-born adults, Asian and Pacific Islander immigrants were more, not less, likely to report that their health was good or better. This finding, coupled with the diminution of the effect among those who had been in the United States for a brief period of time, was consistent with both the migration selectivity and acculturation hypotheses. The odds ratios pertaining to activity limitations provided even stronger support for the validity and complementarity of these hypotheses. Immigrants who had resided in the United States for all three durations studied were at significantly less risk of limitations in their daily activities than were Asians and Pacific Islanders born in the United States, and there was a monotonic increase in the odds ratios (odds ratio (OR) = 0.45, OR = 0.65, and OR = 0.73) as duration increased from 04 to 59 to 10 years or more, respectively, indicating that the greater the number of years immigrants had lived in the United States, the more similar they became to Asian and Pacific Islanders who were US born. This perfectly consistent pattern was also evident with regard to bed days.
The differentials in health status among Asian and Pacific Islander subgroups, net of the effects of immigrant status and a large number of other factors (listed in both the text and in the stub column of table 3), were also quite striking. Compared with the Japanese, all other Asian and Pacific Islander populations reported a greater risk of poor or fair health. By far the highest risk was observed for the Vietnamese (OR = 3.46), but the odds ratios for Koreans, Pacific Islanders, and Other Asians approached or exceeded 2.0. As would be expected on the basis of respondent-assessed health, except for the Chinese, activity limitations tended to be more prevalent among all other Asian and Pacific Islander groups than among the Japanese. Nevertheless, after adjustment for immigrant status and other potential determinants of activity limitations, the odds ratios for the Chinese (OR = 0.90) and Koreans (OR = 1.15) differed only slightly from that of the reference group regarding this outcome. Regarding bed days, the only statistically significant difference across Asian and Pacific Islander populations in the full model was that Pacific Islanders were more likely to have spent a week or more sick in bed (twice as likely than the Japanese).
Multivariate models of physician visits and medical care access
Baseline model. The first panel of table 4 presents estimates of the effects of immigrant status on annual physician visits and regular access to medical care, unadjusted and without distinction by national origin, for Asians and Pacific Islanders. Compared with the native born, physician visits were less common among immigrants. Foreign-born adults who had been in the United States for less than 10 years were also three to four times more likely to have no regular source of medical care. For immigrants of long duration, only that odds ratio for three or more physician visits was significant. However, before drawing conclusions about access to health care, we constructed models that adjusted for health status as well as socioeconomic and demographic variables.
Multivariate model. Controlling for health and the other variables listed in the stub column of table 4 modestly reduced the influence of the effect of immigrant status on physician visits and regular access to medical care, but the pattern and levels of significance of the associations remained the same. Immigrants of all durations continued to be significantly less likely to have made three or more visits to a physician in the past year, and, with the exception of long-term residents, they were also significantly less likely to report one or two annual visits. In the adjusted model, the odds of having no regular source of medical care remained strikingly large for immigrants who had resided in the United States for less than 10 years. Thus, it appears that immigrants tend to be underserved compared with US-born Asians and Pacific Islanders. In the adjusted model, just as for health status per se, immigrant use of health care began to more closely resemble conditions among the US-born adults as duration increased. Regarding health status, while this pattern indicated a worsening of the immigrants' situation, for both regular access to medical care and physician visits, the pattern suggested an improvement.
Only a few significant differences were found across Asian and Pacific Islander national origin groups with regard to physician visits and having a regular source of medical care, but those differences that did emerge were notable. Vietnamese and Koreans provided a striking contrast. The odds of visiting a physician three or more times were 50 percent higher for Vietnamese. Conversely, Koreans were significantly less likely to visit a physician at all. Again, the results with respect to medical care were consistent in that the odds ratio for Koreans having no regular care was almost 90 percent higher (OR = 1.87), whereas the odds ratio for Vietnamese was less than unity (but not statistically significant). A plausible explanation for the opposite positions of the Koreans and Vietnamese concerns differences in health insurance coverage. Examination of several Asian populations has shown that Koreans are the most likely to have no medical insurance of any type; specifically, 45.3 percent of Koreans in that study were not covered at all, while fully 40 percent of Vietnamese were covered by public health insurance, perhaps because of a heavy concentration of refugees in that population (33).
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DISCUSSION |
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Descriptive tabulations (which included the White majority) support the view that Asians are a relatively healthy group, but evidence also exists that such a generalization should be qualified. Although the health of most Asian and Pacific Islander groups appears to be as good as or superior to that of Whites in terms of most indicators, the respondent-evaluated health of Pacific Islanders and Vietnamese was worse, and a higher proportion of Pacific Islanders was bedridden for a week or more because of illness or disability.
Regression estimates that emerged after adjustment for a wide range of factors demonstrated that the health of Asian and Pacific Islander immigrants is superior to that of their native-born counterparts. Immigrants not only perceived they were healthier but also reported fewer activity limitations and bed days, and nearly all coefficients linking immigrant status to health status were highly statistically significant. Moreover, there was an almost perfectly consistent pattern of deterioration in health as length of residence in the United States increased.
Even after control for the powerful effect of immigrant status (along with other factors), health status varied substantially across Asian and Pacific Islander subpopulations. All other Asian and Pacific Islander groups seemed to be either less healthy or not significantly different in health status from the Japanese reference group. In particular, Vietnamese (with the recent and dramatic history of conflict in their nation of origin), Other Asians (which includes a substantial number of refugees), and Pacific Islanders (whose health is apparently compromised by a greater tendency toward obesity and heavier cigarette smoking) (35)) are two to three-and-a-half times more likely to report poor or fair health and, except for Other Asians, are much more likely to encounter activity limitations. In addition, use by Asian and Pacific Islander immigrants of formal medical care increased with duration of immigration. In this instance at least, the strong tendency for the foreign born to become more similar to the native born the longer the former resided in the United States may be regarded as an advantage rather than a disadvantage.
Our study is subject to a number of limitations. One is the familiar problem of lack of information on attributes and conditions that would further advance our understanding of the outcomes of interest. A comparison of Chinese with Koreansinteresting in and of itself because of the confluence of similarities and differences that characterizes these two groupswould provide specific illustrations for what might otherwise legitimately be viewed as simply a conventional and substantively empty admission of imperfection. The adjusted model showed that both groups were at low risk of illness severe enough to require bed rest. However, the odds for Koreans reporting health that was only fair or poor were much higher than the odds for Chinese, yet Koreans were most unlikely to have visited a physician in the past year or to have access to health care.
The explanation for the relatively good health of Chinese may lie in the fact that they, similar to Japanese, have a long history of settlement in the United States (note that the explanation suggested here is in terms of a contextual variable (length of time an immigrant group has been established at destination), not the length of time an individual immigrant has resided in the United States). That is, some quality of life and health advantages may accrue for groups that have had a longer period in which to develop positive social, economic, and political adaptations to a host society. Koreans who are, in a historical context, a "newer" immigrant group might well be expected to evidence poorer health. The observation that they are also the group least likely to visit a physician or to have a regular source of health care may be explicable partially in terms of their cultural preferences for traditional practitioners of "ethnomedicine" (36) and partially in terms of the large numbers of Koreans lacking health insurance (33
). Thus, it may be that variation in the health of minority groups, especially those comprising a large number of immigrants, can be fully understood only by taking into account additional factors, such as immigration history and diversity of cultural norms and values, for which data suitable for inclusion in statistical models are scant or absent (36
, 37
).
It might also be useful to conduct period-specific analyses. For example, the composition of pre- and post-1965 immigrant streams appears to differ substantially (17), and the same may well be true of other temporal cutpoints when US immigration law shifted course. Furthermore, a person's health status and whether he or she has systematic access to health care must depend on not only that person's financial circumstances and living arrangement (for which we controlled) but also whether he or she has medical insurance. In addition, it might be more informative if finer distinctions were made with respect to health status. Finally, although the NHIS provides a large number of cases by typical standards, if a separate investigation of specific Asian and Pacific Islander populations is attempted, cell sizes become too small to permit stable estimates to be derived from multivariate models of the sort estimated here.
Despite these and other limitations, the present research makes it clear that immigration status exercises a powerful influence on the health of Asians and Pacific Islanders. Moreover, there is considerable support for the proposition that immigrant status is crucial to health in general and to the validity and complementarity of the positive immigration selectivity and acculturation hypotheses in particular.
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ACKNOWLEDGMENTS |
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The authors thank Starling G. Pullum for her insightful comments and computing assistance.
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NOTES |
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REFERENCES |
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