New Directions for Public Health Research on the Health and Health Care of Undocumented Immigrants

In 2017, approximately 10.5 million undocumented immigrants lived in the United States. Although the number of undocumented immigrants has declined over the past decade, this estimate is triple that of the population size in 1990, when there were 3.5 million undocumented immigrants.¹ According to a recent population-based study of California residents, undocumented immigrants exbibit worse patterns of health care access and use than US-born residents or immigrants who are naturalized or hold green cards.² This is not necessarily surprising given that undocumented immigrants have largely been left out of policies aimed at improving insurance coverage and access to care.

Some states, including California, have used state Medicaid programs or organized county indigent care programs to care for undocumented youths and young adults. However, most states have excluded undocumented immigrants from public insurance programs, and they are explicitly excluded from the marketplace exchanges and the federally funded Medicaid expansions provided by the Patient Protection and Affordable Care Act.^3,4

In their article in this issue, Ro et al. (p. 2019) used administrative data from the Los Angeles County + University of Southern California Medical Center to describe differences in illness severity, length of hospital stays, and repeat hospitalizations between undocumented immigrant patients and full-scope Medi-Cal (California’s Medicaid program) patients. To classify undocumented immigrants, they used as a proxy restricted-scope Medi-Cal, which is limited to emergency and pregnancy care for low-income Los Angeles residents who meet the Medi-Cal income threshold but do not meet immigration status requirements (e.g., US national, lawful permanent resident).

Their main findings were that younger (18–64 years) undocumented immigrant patients had less severe illness and spent less time in the hospital than younger Medi-Cal patients, whereas older (≥ 65 years) undocumented patients also had less severe illness but had lengths of stay that were similar to those of older Medi-Cal patients. These findings generally confirm previous reports indicating that undocumented immigrants are unlikely to burden the safety net because of their healthy profiles and underuse of health services.^2,5

This study is an important contribution to the growing literature on the health and health care needs of undocumented immigrants. It is also one of the first studies in which administrative data have been used to understand patterns of hospital care use and illness severity among undocumented immigrants requiring hospitalization. The study, however, must be put into the context of the broader empirical literature on the topic.

For example, the authors used data from patients needing hospitalization from a safety net hospital in Los Angeles that serves a very vulnerable population with complex health needs, including many low-income patients on Medicaid or without insurance and a large homeless population. Thus, the observations are not necessarily representative of the undocumented population in Los Angeles County, the state of California, or nationally. Also, the strategy to identify undocumented immigrant patients through restricted-scope Medi-Cal creates potential selection bias among patients who are poor and have high medical needs. The authors attempted to account for this problem by controlling for homeless status and using an inverse probability weighted regression adjustment; however, the unobserved differences between the undocumented immigrant and Medi-Cal populations are still likely to mispresent the health advantages of undocumented immigrants.

Public health researchers have long observed a health advantage for recent immigrants, an advantage commonly referred to as the “healthy immigrant effect.”⁶ This phenomenon is the notion that recent immigrants are in better health, on average, than US-born residents or immigrants who have been in the country for a long period of time. Because access to and use of health care tend to be poor among undocumented immigrants, it has been assumed that in general they are at high risk for poor health outcomes; however, others have posited that they are protected as a result of the healthy immigrant effect.⁷

Indeed, Ro et al. concluded that despite poor access to care, undocumented immigrants had less severe illness than their Medi-Cal counterparts. It should be noted, however, that their measure of health trends was based on illness severity as measured by the relative risk of mortality among hospitalized patients. Most researchers assessing the health advantages of immigrants have used measures such as self-rated health status, physician-diagnosed chronic diseases, and health behaviors.^2,8,9

In 2017, it was estimated that 66% of undocumented immigrant adults in the United States had been in the country for more than 10 years, as compared with 41% in 2007. With acculturation and more time spent in the United States, it has been observed that the advantages of the healthy immigrant effect decline.¹⁰ Undocumented immigrants, particularly those who have been in the country for many years, would in theory benefit less from the healthy immigrant effect. A recent California study showed that the immigrant health advantage with respect to cardiovascular behavioral health risk did not apply to undocumented immigrant Latino men whose health behaviors were similar to those of US-born Latino men; however, health patterns were better among undocumented immigrant Latinas.⁸ Similarly, a study of Latinos in Los Angeles County revealed that undocumented immigrants who had been in the United States for short durations had worse self-reported health than the US-born individuals.⁹

In 2018, it was estimated that 880 000 undocumented immigrants lived in Los Angeles County and that 680 000 (78%) of them were Latino.¹¹ In a study of California Latino immigrants, only 25% of undocumented immigrants reported being in excellent or very good health, as compared with 49% of US-born Latinos and 36% of naturalized Latino immigrants, even though undocumented immigrants were less likely to report physical health problems such as obesity, high blood pressure, asthma, and diabetes.² The lower odds of undocumented immigrants ever having been told by a provider that they had a physical health condition were a function of their having significantly worse access to care than other groups.³ Furthermore, some of the discrepancy, at least with respect to self-rated health, might be attributed to the measure’s response categories and the Spanish translation of “fair.”¹²

Immigrants have long been underserved in the US health care system, particularly those who are uninsured or do not have legal authorization status. The recent expansion of Medicaid coverage to undocumented immigrants up to the age of 26 years in California and new indigent care programs such as MyHealthLA are examples of initiatives at the state and local levels that can partly address health care inequities among immigrants. Policy efforts to expand health insurance coverage to the growing aging undocumented immigrant population should include assessments of the situation in California, where the state legislature recently decided to expand Medi-Cal coverage to low-income undocumented immigrants 50 years or older. Undocumented immigrants 26 to 49 years old without insurance will continue to have some level of access to primary, specialty, and inpatient care through California’s indigent care programs, although these programs do not offer the same financial protection as private insurance or Medi-Cal.

Public health research on the health and health care of undocumented immigrants in the United States is quickly evolving. The Ro et al. article augments what has been observed in population-based studies, and it raises some interesting areas of inquiry for the field. The extent to which the healthy immigrant effect applies to undocumented immigrants, especially as they live in the country for longer durations and a growing proportion of them are aging, is still open for debate and discovery.⁷ We also need a better understanding of the health care needs of undocumented immigrants to inform policies and programs aimed at addressing health inequities. As the demography of the immigrant population continues to shift, it is imperative that public health research, practice, and advocacy focus on ways to engage all immigrants, especially those who are undocumented.

CONFLICTS OF INTEREST

The authors have no potential conflicts of interest to disclose.