Oral health status and the epidemiologic paradox within latino immigrant groups

An appreciation for the diversity between ethnic groups within the United States has emerged in the dental literature, especially with respect to health and health care needs[1]. The idea of diversity among ethnic groups is even newer and is particularly important when considering Latinos, where the diversity among those covered by the term, “Latinos,” is extensive. The lack of data on Latino sub-populations was the impetus to establishing the national Hispanic Health Research Consortium in 1986. In reviewing twenty-one data collection agencies of the Department of Health and Human Services, Delgado and Estrada[2] found only three that collected data on Mexican Americans and only one that collected data on Puerto Ricans, Cuban Americans and Central-South Americans. Latinos represent the fastest growing minority population in the United States. It is imperative that more attention be paid to the heterogeneity of Latino sub-populations in future studies[3, 4].

Among Latinos, Mexican Americans constitute the largest subgroup at the national, state and local levels[5]. In cities, like Los Angeles, there are many Latino subgroups whose numbers are modest when compared to Mexican-Americans. According to the 2010 U.S. Census, there were 4.7 million “Hispanics” in Los Angeles County, California, which include Mexican-born and U.S.-born Mexicans, Central and South Americans[6]. Los Angeles has become a “social laboratory” for understanding ethnic heterogeneity in health care. The 2010 Census describes the Latino population by origin and includes Cubans, Mexicans, Puerto Ricans, South or Central Americans and other Spanish persons under the collective term of “Hispanic/Latinos”[6].

Ethnicity has been identified in models of health behavior and health services utilization as a significant variable. For example, in Andersen and Davidson’s Behavioral Model (Figure1)[7], ethnicity, like other exogenous variables, such as age and gender, affects the primary determinants of oral health. Within the original version of the model, a patient’s personal characteristics, the dental care system, and features of the external environment, together impact key oral health outcomes. The Behavioral Model has been adapted for this study as a framework to guide the research in determining how ethnicity and other socio-demographic factors can affect oral health status.

The Oral Health Status Index (OHSI) is used in this research as a quantitative means of measuring evaluated oral health status outcomes[8]. It integrates the status of the teeth and periodontium into one numerical score. The OHSI was used by Marcus et al. (1983)[8] to compare low income populations in Los Angeles and New York City and found that the OHSI scores were significantly higher in Los Angeles than in New York. Deporter et al. (1988)[9] used the OHSI to compare capitation enrollees with those enrolled in voluntary dental plans. Manninen et al. (1994)[10] used the OHSI to compare skilled workers enrolled in either fee-for-service or capitation plans and found no difference between these two groups. Lang et al. (1997)[11] utilized the OHSI to compare African-Americans and whites in Michigan and found the index to be an effective measure of clinical oral health status and quantified the disparities in demographic and other variables. Spolsky et al. (2000)[12] established the validity of the OHSI using Latino populations. Otsuru et al. (2006)[13] used the OHSI as an outcome measure to examine the difference between native Japanese and migrant workers and found that the OHSI scores of native Japanese were significantly higher than those of the migrant workers.

Markides and Coreil[14] described the general health status of Mexicans relative to African Americans and whites, documenting the epidemiologic paradox in terms of a number of clinically determined health conditions and also self-perceived health. Other studies have confirmed the epidemiologic paradox for low birth weight[15] and infant mortally[16]. Apparently, clinical oral health may also demonstrate the epidemiologic paradox whereby Latinos born in Mexico have better oral health status than those born in other Latino countries despite low utilization and less access to dental care. According to Markides and Coreil[14], possible explanations for this difference may be related to selected migration, whereby Mexicans are more likely to be from rural areas while other Latinos are more likely to come from urban areas. This may be reflected in oral health practices and diet. Extended family support is another factor identified by Markides and Coreil and is a more subtle issue since Latino cultures tend to have strong family ties. In this paper we examine the epidemiologic paradox by comparing differences in oral health status within Latinos, specifically between Mexican immigrants and other Latino immigrant groups.

An adaptation of the Behavioral Model provides the conceptual approach for this study. The exogenous variables include ethnicity and age; while personal characteristics include education and income; and oral health behavior include both positive (flossing) and negative health behaviors (alcoholic consumption and tobacco use).

In an analysis of California residents, comparing whites, African American and Latinos, Hayes-Bautista et al. (1994)[23] characterized the Latino epidemiologic paradox in terms that defy the common wisdom that low-income, less educated groups, such as Mexicans, have low birth weights, high infant mortality, higher rates of heart disease, strokes and cancer, and other chronic diseases. His analysis showed that Mexican rates for these conditions were comparable to whites, even though their educational levels and incomes were lower, they did not access prenatal care and other health care and poverty rates were higher. This study presents a new perspective on the epidemiologic paradox by examining the relative oral health of Mexican and other Latino immigrants. In this study, all things being equal, Latinos who emigrated from countries other than Mexico have a lower OHIS index score compared to Mexican immigrants, indicating poorer oral health.

Education and income did not explain the differences in oral health status between Mexican immigrants and other Latino immigrants as indicated by the regression analysis. However, the epidemiologic paradox appears to exist, indicating that the Mexican immigrant lifestyle tends to promote significantly better oral health than other Latino immigrants. This occurred even though the Latino immigrants from other Latin American countries were exposed to more dentistry than the Mexicans, suggested by the higher number of filled teeth and the higher proportion of missing teeth that were replaced in this population.

Although the subjects from other Latino immigrant groups had more exposure to rehabilitative dental services, this did not result in better oral health according to the OHSI. This was primarily due to the effects of missing teeth on oral health because function and replacement of missing teeth do not restore oral health to the same extent as absence of disease. Therefore, the fact that Latinos who did not emigrate from Mexico had more exposure to dental treatment was not reflected in higher oral health status.

Similar to the study findings of Hayes-Bautista et al.[23], notably that while Mexicans had less prenatal care compared to whites their outcomes were comparable, our case suggests that Mexicans tend to have better oral health than other Latino immigrant groups while receiving less care. This may be due to the nature of the Mexican diet and high familial social support, which may reinforce good oral health practices. Another factor may be their reliance on community health fairs, which promote preventive practices. This is due in part to the fact that Mexican communities have existed in Los Angeles for a long time, enabling them to establish networks of health promotion even though access to care is a barrier for this population.

Although this study is limited to a community-based sample, which thereby limits its interpretation and generalization, the results are important because they provide insight into populations that have been understudied. The study also demonstrates that place of birth (i.e., country/region of origin) is a significant factor in bringing to light differences in oral health outcome measures between Mexican immigrants and other Latino immigrant groups. Additionally, this study reinforces the concept of epidemiologic paradox within the Latino population; however, better models are clearly needed to capture more subtle differences within and between ethnic groups.

VWS is an epidemiologist with experience in large national surveys and in conducting clinical trials of preventive agents. MM is a health service researcher who studies oral health status. CDM is a sociologist who conducts research on ethnicity, immigrant populations and oral health. IDC is a health sociologist who has conducted research on complementary and alternative medicine and oral health quality of life. CAM is a medical anthropologist who has conducted community-based research in trauma, chronic disease, and oral health.