Evidence for an epidemiologic paradox for the U.S. Hispanic population was perhaps first clearly uncovered by Teller and Clyburn (1974)
, who, using data from the State of Texas, reported that the infant mortality rate for the Spanish-surname population was slightly lower than that of non-Hispanic whites in the mid-1960s. In a seminal review on the topic about a decade later, Markides and Coreil (1986
:253) coined the concept “epidemiologic paradox,” summarizing it as follows:
Despite methodological limitations of much of the research, it can be concluded with some certainty that the health status of Hispanics in the Southwest is much more similar to the health status of other whites than that of blacks although socioeconomically, the status of Hispanics is closer to that of blacks. This observation is supported by evidence on such key health indicators as infant mortality, life-expectancy, mortality from cardiovascular diseases, mortality from major types of cancer, and measures of functional health. On other health indicators, such as diabetes and infectious and parasitic diseases, Hispanics appear to be clearly disadvantaged relative to other whites.
Note that Markides and Coreil (1986
; also see Markides and Eschbach 2005
) did not define the paradox as better
health or mortality for Hispanics compared with non-Hispanic whites, nor did they argue that the paradox applied to all health and mortality outcomes. Instead, they defined the paradox with regard to Hispanics exhibiting some key health and mortality outcomes that are much more similar
to whites than to blacks even though the overall socioeconomic status of Hispanics is much closer to that of blacks than to that of whites.
Three explanations have been offered for the paradox. The first is immigration selectivity. Here, the argument is that immigration is positively selective on good health (Franzini et al. 2001
; Markides and Eschbach 2005
). Thus, for example, selectively healthy immigrant women of childbearing age are more likely to give birth to healthy infants in the United States in comparison with their native-born counterparts who are not selectively healthy in the same way.
Second, some have suggested that cultural factors tend to encourage healthy behaviors and strong family ties among Hispanics in the United States, particularly in the immigrant generation, helping to explain the relatively favorable observed health and mortality patterns that define the paradox (Franzini et al. 2001
; Scribner 1996
). Some have suggested that a negative acculturation process may work to help deteriorate the largely positive health and mortality outcomes among immigrant Hispanics over time and across generations, although data limitations have prevented a rigorous test of this hypothesis (Cho et al. 2004
; Jasso et al. 2004
Most recent demographic work in this area of study has focused on the third explanation for the paradox, which is also the main focus of the current study: namely, data quality issues. Indeed, recent demographic work in this area, mostly focusing on adult mortality, has attempted to account for the effect of out-migration on Hispanic mortality estimates in the United States, made corrections for questionable data, and dealt with the issue of disparate race/ethnicity reporting across different data sources and across time (Abraido-Lanza et al. 1999
; Elo et al. 2004
; Hummer et al. 2004
; Liao et al. 1998
; Palloni and Arias 2004
; Rosenberg et al. 1999
; Smith and Bradshaw 2006
; Swallen and Guend 2003
; Turra and Elo forthcoming
). Although these studies concur that U.S. government-reported Hispanic adult mortality rates (e.g., Kochanek et al. 2004
) are too low because of data quality issues, there is not yet consensus with regard to whether Hispanic adult mortality rates are actually slightly lower than, equivalent to, or higher than mortality rates for non-Hispanic whites. The answer to that question surely depends on the Hispanic subgroup in question, whether immigrant Hispanics are distinguished from native-born Hispanics, and the specific age groups that are examined.
Most central to the issues in the current paper is recent work by Turra and Elo (forthcoming), who examined the impact of out-migration from the United States (to Mexico and elsewhere) on reported mortality rates among primary beneficiaries of social security (those aged 65 and older) in the United States. They found evidence that both Hispanic and non-Hispanic white out-migrants from the United States do indeed exhibit higher mortality than persons in their same racial/ethnic group who do not out-migrate. However, even when such out-migration is taken into account, Hispanic mortality in the United States for social security beneficiaries aged 65 and older remains between 11% and 18% lower than that of non-Hispanic whites, depending on the specific age/sex group in question. This happens primarily because the volume of out-migration is simply not large enough to significantly influence adult mortality rates in the United States. Thus, although they show evidence that is consistent with what some refer to as a “salmon bias” (Abraido-Lanza et al. 1999
) in terms of Hispanic mortality in the United States, the overall magnitude of its effect on Hispanic versus non-Hispanic white mortality patterns was found to be very slight.
Turning to infant mortality, historical demographic work has found that infant mortality rates for the Spanish-surname population of the United States were not always similar to, or lower than, those for non-Hispanic whites. In fact, they were much higher than those of whites throughout the first half of the twentieth century (Forbes and Frisbie 1991
; Gutmann et al. 2000
). By 1980, however, data sets from Texas and California showed parity or near-parity between the infant mortality rates of the Hispanic and non-Hispanic white populations (Forbes and Frisbie 1991
; Williams, Binkin, and Clingman 1986
). These findings were later echoed in national-level data on infant mortality (Becerra et al. 1991
; Hummer, Biegler et al. 1999
; Singh and Yu 1996
). Nevertheless, there was (and continues to be) some skepticism that the relatively low infant mortality rate among Hispanics was (and is), at least in part, attributable to the underreporting of Hispanic infant deaths in the United States, particularly within the Mexican-origin population (Palloni and Morenoff 2001
; Williams et al. 1986
). The most relevant reason for underreporting, at least during the past few decades, is consistent with that discussed earlier from the adult mortality literature: namely, that out-migration of women and their U.S.-born infants to Mexico or elsewhere results in an underregistration of infant deaths in the United States. Such out-migration of women and infants is not necessarily health based, as defined by the concept of the salmon bias among older adults. However, the general phenomenon of out-migration of women and infants from the United States for health or other reasons would result in an underregistration of infant deaths in the United States.
Recently, for example, Palloni and Morenoff (2001
:152−53) reviewed and critiqued the literature on the epidemiologic paradox. Specifically writing about possible explanations for the epidemiologic paradox with regard to infant mortality, they highlighted the issue of underregistration:
The first explanation (the under-registration of infant deaths in the target population) has been dismissed outright, but probably too quickly and hastily. We are not aware of any large-scale effort to actually test this hypothesis, at least not in a way that is comparable to what has been done for the case of white-black differentials in adult mortality in the U.S. (Preston et al. 1996
). Instead, we find assessments of some data sets (e.g., Bexar County) where the authors assert that errors of under-registration could not reasonably be large enough to account for the observed patterns of infant mortality differences (Forbes and Frisbie 1991
). Admittedly the claim for that particular data set may be compelling but as a general explanation does not have the power to close the case once and for all. The important point is that this alternative explanation has not yet been excluded and may, together with other problems, undermine the case for a paradox.
Clearly, it is plausible that Mexican-origin women who give birth in the United States return to Mexico. Such a phenomenon would result in a birth being registered in the United States, which increases the denominator of the Mexican-origin infant-mortality rate in the United States. However, if U.S.-born out-migrating infants die in the first year of life in Mexico, such deaths are not recorded in the United States. Thus, the resulting count of deaths in the numerator of the U.S. infant mortality rate is artificially low. No data system is in place for linking infant deaths that may occur in Mexico back to the corresponding birth certificate records in the United States.
This paper makes no claim that such a process cannot, or does not, occur. Rather, this paper sheds light on the magnitude of this issue and its relevance for the epidemiologic paradox by carefully calculating detailed, age-specific infant-mortality rates for the key ethnicity/nativity groups in question. Given the complete registration of births and infant deaths in the United States (Bryan and Heuser 2004
:61), the extremely high match rate between infant deaths that occur in the United States with their corresponding birth certificates in the vital statistics data set we use (National Center for Health Statistics 2000
), and the strong unlikelihood that mothers with newborn infants (less than 1 hour, 1 day, 1 week, or even 1 month old) would leave a country that has extremely advanced medical technology (particularly if their infant was born early and/or small, or was otherwise at risk of death), we are very confident that the detailed mortality rates in the neonatal period that we calculate are quite accurate and have little chance of being influenced by the underregistration of infant deaths. Because out-migration becomes a more logical possibility later in infancy, the rates that we calculate for the postneonatal period are more subject to possible underregistration of infant deaths in the United States. We complete the analysis by providing approximations of the number of women and infants who would need to out-migrate from the United States for the observed rates of infant mortality among the Mexican immigrant population to be seriously biased. We conclude that the epidemiologic paradox, at least in terms of infant mortality among the Mexican-origin population in the United States in relation to non-Hispanic whites and non-Hispanic blacks, is not a data artifact.