Acculturation is defined as continuous, firsthand contact with other cultures functioning at both group and individual levels 1. Such contact is an iterative process by which an individual assimilates with the sociolinguistic and cultural norms of their host country, thereby facilitating access to certain products and services, such as health care. Acculturation is reflected in our culturally diverse society, calling for a greater understanding of the environmental and cultural impact on health 1.

Higher levels of acculturation have been associated with various health outcomes, including mortality 234, adverse health behaviors 5, mental health disorders 6 and heart disease status, such as hypertension 78. For example, hypertension rates have been associated with the acculturation continuum in middle aged Mexican Americans 8. After controlling for potential predisposing (age, sex, marital status), enabling (insurance, employment), and need (number of chronic diseases, physical symptom scale, self-rated health, worry about health) factors, Mexican Americans who were more acculturated to U.S. norms had lower hypertension rates than the less acculturated subjects 8. Thus, the link between acculturation and disease status may be explained by one's ability to identify and understand their health status within the context of a host country whose socio-cultural norms have not been assimilated to that individual. The role of acculturation regarding the mental health status of Hispanics with family support can function as a moderator or mediator and is differential across immigration status 910. Such research findings support the importance of including psychosocial risk factors and length of stay in the host country when examining acculturation's influence on health.

Self-reported health (SRH), a robust and well validated predictor of future mortality for all racial/ethnic groups, has been differentially reported by Hispanics compared to whites, especially based on their acculturation status 111213. A study by Shetterly et al. 14 revealed that Hispanics were 3.6 times more likely to report fair or poor health compared to whites, with acculturation being the strongest explanatory factor. Another study using data from the National Health Interview Survey (NHIS) from 1989-1994 found poor SRH as a weak predictor of subsequent mortality risk among less acculturated individuals 15. However, the association between poor SRH and mortality risk increased with U.S. acculturation, with differential effects noted across language, place of birth, and length of stay in the U.S. 15. Cultural practices and linguistic competency of the individual across a span of time in a host country can moderate or exacerbate access to healthcare providers and the ability to secure insurance. Furthermore, the role of acculturation, specifically one's level of assimilation to the health behaviors of the host country, may affect how health is perceived.

Although studies have assessed how acculturation status predicts the status of various health outcomes, it remains unclear whether acculturation status truly predicts one's SRH after taking into account socioeconomic measures, psychosocial factors, health behaviors, chronic disease status, and access to care measures. Moreover, the investigators propose that these factors can be more clearly assessed using an adapted framework developed by Andersen 16. We hypothesized that lower levels of U.S. acculturation are associated with poor/fair SRH status and this relationship is confounded by predisposing, enabling, and need factors related to the Andersen model discussed below.

Descriptive characteristics of the NTHH participants are presented in Table 1. Although it is not shown in the table, 98.4% of the participants were of Mexican-origin. More than half of all Hispanics reported excellent/very good/good health, but Mexican-oriented Hispanics rated their health lower than Anglo-oriented Hispanics. Mexican-oriented Hispanics were more likely to report less than a high school education than Anglo-oriented participants or income below $20,000. The majority of Mexican-oriented participants reported access to a primary care yet had no health insurance.

Logistic regression results are found in Table 2. Bivariate regression analyses revealed Mexican-oriented Hispanics were over 3 times more likely to report fair/poor health compared to Anglo-oriented Hispanics. Other statistically significant predictors included education, sense of control, stress, and depression scores in that participants with education levels less than high school were 4.16 times more likely to report fair/poor self-health ratings compared to those who had higher levels of education. In addition, Hispanics who reported high levels of stress or depression were 1.07 and 1.08, respectively, times more likely to report fair/poor health. Conversely, Hispanics who reported a higher sense of control were less likely to report fair/poor health.

Multiple logistic regression results can also be found in Table 2. In model 1, acculturation was not significantly associated with poor/fair health once predisposing factors were included in the model. High education status (i.e., high school or greater) remained a protective factor from fair/poor health status. In models 2 and 3, Mexican-oriented acculturation remained significantly associated with fair/poor health and was not impacted by enabling or need factors, respectively. Model 4 included only variables that were statistically significantly related to the independent or dependent variable within the bivariate and multivariate models. This final model found acculturation to be significantly associated with fair/poor health status. Depression symptomatology was the only other variable that remained significantly associated with fair/poor health in all models.

The study's aim was to better understand the relationship between acculturation and SRH. The importance of this research results from conflicting evidence in the literature and perceptions of Hispanic health. Many health disparity researchers view Hispanics as a "healthy" but economically-disadvantaged population and have used terms such as the "Hispanic paradox" 27. However, it remains unrecognized that the mental and physical suffering and morbidity is as important as mortality outcomes and surrogate disease measures. Moreover, extensive research has demonstrated that acculturation can have both negative and protective effects depending on the outcome of interest, such as certain health behaviors or health care use 28. Therefore, SRH was chosen as the outcome variable of interest in the present study since it conceptually functions as a composite measure of mental and physical well being. In addition, this form of health status reporting has been shown to be predictive of adverse health outcomes, including overall mortality for all racial/ethnic groups 13.

The Andersen socio-behavioral approach taken by this study allowed a better understanding of how acculturation impacts health status by systematically assessing clusters of determinant factors and their impact on SRH. Using this approach, Mexican-oriented acculturation remained an independent predictor of fair/poor health in the final model. This finding supports the notion that self-rated health may be affected by a person's level of acculturation while controlling for certain predisposing, enabling, and need factors. Although data are not shown, the authors conducted multiple logistic regression analyses for each predisposing variable with acculturation and only education was found to function as a confounder.

Previous research has argued that acculturation studies have often overlooked the importance of socioeconomic status to better understand the relationship between acculturation and health outcomes 29. In fact, this study's results supported the theory that acculturation functions in a greater social context, and not only at the individual level, with education being one of the important variables to consider. Our results were similar to that of Markides and Martin 30 who suggested lower SRH of Mexican Americans in Texas was solely due to education and income. Education may have improved health by increasing effective agency and physical functioning 22 and enhanced a sense of control that enabled one to select a healthy lifestyle 31. Other studies have reported associations between lower SRH with lower education and income 323334353637. The variations among studies assessing the relationship between acculturation and outcomes, such as health behaviors and disease markers, also demonstrated differences on how education impacts these associations. Education functioned as a confounder in some studies while not in others. There are many possible explanations for these inter-study variations, including geographic variation, differences among Hispanic subgroups or other races/ethnicities, and how acculturation was measured 293839. Many studies utilized proxy measures of acculturation, such as the number of years residing in the United States or primary language spoken. However, it has been suggested that these measures assumed stereotypes and were not accurate measures of acculturation 29.

Although not measured in the current study, the association between acculturation, determinants of health status, and health status is conceptually thought to be mediated by health care use and health behaviors 16. However, conflicting evidence exists in the literature since most studies related to health behaviors have found Anglo-oriented acculturation to be associated with higher rates of poor behaviors such as smoking and obesity 36. Conversely, Mexican-oriented acculturation has been associated with lower health care use and health status. One possible explanation is increased reporting of lower SRH among Mexican-oriented Hispanics. One study found Hispanics with a lower education status tended to make more extreme choices when responding to questions in surveys compared to those with higher education levels 40. Also, Hispanics might have been less willing to rate their own health highly because it was not a commonly accepted practice among older, more traditional Hispanics 14. Another potential explanation is that Hispanics tended to somatize their mental and emotional health into physical health leading to lower ratings of health 41.

There are several strengths and limitations to the study that are worth noting. Although statistically significant results were found, the sample size was relatively small. Also, caution is advised when generalizing the results to other geographic regions since variation may exist. Hispanics were discussed as a homogenous group when, in fact, there may be significant variations among Hispanic sub-populations. The strengths of this study include the use of a validated instrument to measure acculturation and psychosocial measures, which past literature may not have addressed. However, the subjective nature of surveys must be taken into perspective. As mentioned previously, response to study questions may be influenced by one's educational level or other related factors and consequently skew study results. Finally, the cross-sectional nature of this study prohibits any assumptions of causality.

Larger statistical samples are needed to examine how psychosocial variables and acculturative factors may contribute to the causal pathways of various disease outcomes. In addition, more research that promotes the use and improved definition of acculturation measures as it relate to theoretical models of public health will increase knowledge of the role of acculturation in Hispanic health behaviors, health outcomes, and health care use 28. Such research findings will contribute to the design of culturally sensitive prevention and treatment strategies for racially/ethnically diverse and immigrant populations.

The authors declare that they have no competing interests.

KLJ carried out data collection, entry, statistical analysis and manuscript development. JFC helped conceive the study as co-investigator and reviewed the manuscript. KGF participated in statistical data management, analysis, manuscript development, review, and submission. KC participated in the study's conception and design and manuscript review. RC was the primary investigator, helped conceive the study, conducted data analysis, helped draft and review the manuscript. All authors read and approved the final manuscript.

Katandria Johnson, MA, MS, CCC-SLP is a DrPH social and behavioral sciences of public health graduate student, linguist, and trilingual speech-language pathologist. She also works as a research associate for the Primary Care Research Institute at the University of North Texas Health Science Center at Fort Worth. Research interests include international health and health disparities among pediatric populations with special healthcare needs.

Joan F. Carroll, Ph.D., F.A.C.S.M. is an Assistant Professor in the Department of Integrative Physiology at the University of North Texas Health Science Center. Dr. Carroll's research interests include cardiovascular function in obesity, using both human and animal models, and ethnic disparities in the relationship between body composition and inflammation.

Kimberly Fulda, DrPH is an Assistant Professor in the Department of Family Medicine and the Associate Director of the Primary Care Research Institute at the University of North Texas Health Science Center. Dr. Fulda's specialty is biostatistics and research design. Her research interests include children's health, maternal and child health, as well as public health.

Kathyrn Cardarelli, PhD is an Assistant Professor in the Department of Epidemiology and Director of the Center for Community Health at the University of North Texas Health Science Center. Dr. Cardarelli's research interests include the influence of social and psychosocial factors (including socioeconomic position, discrimination, sense of personal control, and social support) on chronic disease and pregnancy outcomes and mechanisms involved in these relationships; community-based research; and policy and methods related to population health and health disparities

Roberto Cardarelli, DO, MPH is an Associate Professor in the Department of Family Medicine and the Executive Director of the Primary Care Research Institute at the University of North Texas Health Science Center. Dr. Cardarelli's research interests include improving primary care practice, physicians disciplined by state medical boards, chronic disease management, evidence-based reviews, and health disparities in point-of-care practice. His main interest in medical care is chronic disease management.