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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
J Epidemiol Community Health. Author manuscript; available in PMC 2010 November 1.
Published in final edited form as:
PMCID: PMC2773541

The health of homeless immigrants

Shirley Chiu, MA,1 Donald A. Redelmeier, MD, MSHSR,2,3 George Tolomiczenko, PhD, MPH, MBA,4,5 Alex Kiss, PhD,6 and Stephen W. Hwang, MD, MPH1,2



This study examined the association between immigrant status and current health in a representative sample of 1,189 homeless people in Toronto, Canada.


Multivariate regression analyses were performed to examine the relationship between immigrant status and current health status (assessed using the SF-12) among homeless recent immigrants (≤10 years since immigration), non-recent immigrants (>10 years since immigration), and Canadian-born individuals recruited at shelters and meal programs (response rate 73%).


After adjusting for demographic characteristics and lifetime duration of homelessness, recent immigrants were significantly less likely to have chronic conditions (RR 0.7, 95% CI 0.5 to 0.9), mental health problems (OR 0.4, 95% CI 0.2 to 0.7), alcohol problems (OR 0.2, 95% CI 0.1 to 0.5), and drug problems (OR 0.2, 95% CI 0.1 to 0.4) compared to non-recent immigrants and Canadian-born individuals. Recent immigrants were also more likely to have better mental health status (+3.4 points, SE ±1.6) and physical health status (+2.2 points, SE ±1.3) on scales with a mean of 50 and a standard deviation of 10 in the general population.


Homeless recent immigrants are a distinct group who are generally healthier and may have very different service needs compared to other homeless people.

Keywords: homelessness, migration and health

Immigration has always been a determinant of population growth of North America. In 2006, 37.5 million (12%) of the total U.S. population were foreign-born.[1] Similarly, immigrants represented 6.2 million (20%) of the total population in Canada.[2] These individuals often display the “healthy immigrant effect,” that is, being generally healthier than their native-born counterparts. The “healthy immigrant effect” is believed to be strongest among recent immigrants since screening tends to disqualify individuals with serious medical conditions and also because younger, healthier, and better educated individuals may self-select into the immigration process. Over time, however, this effect diminishes, and the health status of foreign-born individuals tends to converge towards that of non-immigrants.[3-6]

The health of immigrants has been assessed using various measures such as life expectancy, the presence of disability, and, most commonly, the prevalence of chronic conditions.[7] Studies in the U.S. and Canada demonstrate that recent immigrants are less likely than native-born persons to have chronic conditions, but this disparity decreases substantially over time.[3-4, 8-9] Those immigrating in the past year, 1-5 years ago, 5-10 years ago, 10-15 years ago, and ≥15 years ago were 56%, 52%, 48%, 49%, and 24% less likely, respectively, to report a chronic condition than U.S-born individuals.[8] Data from the National Population Health Survey in Canada showed that the prevalence of chronic conditions increased among immigrants who had lived in Canada for >10 years and approached levels comparable to that seen in Canadian-born individuals.[9]

A smaller number of studies have examined mental health and substance use among immigrants to the U.S. and Canada.[10-14] The U.S. literature has focused primarily on Hispanic immigrants. Most studies found that mental health and substance use is less common among immigrants compared to non-immigrants.[11-13] Moreover, after increased length of residence in the host country, there was an equalization of risk for mental health and substance use problems between immigrants and non-immigrants.[10-14]

It is uncertain to what degree the “healthy immigrant” effect can be generalized to highly disadvantaged and marginalized groups such as the homeless. There has been a paucity of research on homeless immigrants in general,[15-16] and we are unaware of any study in the peer-reviewed literature that has specifically focused on the health of homeless immigrants. We therefore conducted this study to compare the demographic characteristics and health status of recent immigrants, non-recent immigrants, and native-born individuals in a representative sample of homeless people in Toronto, Canada. The primary goal of this study was to examine the association between immigrant status and current health status.


Setting and Study population

Toronto is Canada's largest city with a population of 5 million, of whom 2.3 million (46%) are immigrants.[17] A representative sample of homeless persons were recruited in Toronto, where about 5,000 individuals are homeless each night, and a total of 29,000 unique individuals use shelters over the course of one year.[18-19] We defined homelessness as living within the last 7 days at a shelter, public place, vehicle, abandoned building, or someone else's home, and not having a home of one's own. Based on a pilot study, we determined that about 90% of homeless people in Toronto slept at shelters, and that 10% did not use shelters but used meal programs.[20] We therefore recruited 90% of our study participants at shelters and 10% at meal programs.

We contacted every homeless shelter in Toronto and obtained permission to enroll participants at 58 (91%) of 64 shelters (20 shelters for men, 12 for women, 6 for men and women, 12 for youths aged 16-25 years, and 8 for adults accompanied with dependent children). The number of beds at each shelter ranged between 20 and 406. Recruitment at meal programs took place at 18 sites selected at random from 62 meal programs in Toronto that served homeless people. Because the goal of recruiting at meal programs was to enroll homeless people who did not use shelters, we excluded individuals at meal programs who had used a shelter within the last 7 days to avoid over-representing those using both.

Recruitment took place over 12 consecutive months in 2004-2005. We stratified enrollment to achieve a 2:1:1 ratio of males without dependent children, females without dependent children, and adults accompanied with dependent children. The number of participants recruited at each site was proportionate to the number of homeless individuals served monthly. We selected participants at random from bed lists or meal lines using a random number generator and assessed their eligibility. We excluded people who did not meet our definition of homelessness, who were unable to communicate in English, and who were unable to give informed consent. We also excluded homeless shelter users who were encountered at meal programs and those who did not have a valid Ontario health insurance number, which was required for tracking of health care use subsequent to the recruitment interview.

Each participant provided written informed consent and received $15 for completing the survey. This study was approved by the research ethics board at St. Michael's Hospital.


Research team members administered the survey to each participant by a face-to-face interview conducted immediately after recruitment at shelters and meal programs. Information on demographic characteristics was collected from the participants. Adults who had any children under 18 years old living with them were considered as being accompanied with children. Participants self-identified their race/ethnicity from categories adapted from the Statistics Canada Ethnic Diversity Survey.[21] The most commonly selected categories were White, Black, and First Nations; all other categories were classified as Other.

Immigrant status was determined based on participants' responses regarding whether they were born in Canada, age when they moved to Canada (if an immigrant), and age at the time of the interview. Participants were defined as recent immigrants if they moved to Canada ≤10 years ago. Participants were defined as non-recent immigrants if they moved to Canada >10 years ago, or as Canadian-born individuals if originally born in this country. The cut-off of 10 years between recent and non-recent immigrants was used because past research suggests that immigrants report a distinctive sense of comfort and familiarity with their new country after approximately one decade.[7]

Participants were asked to identify the single most important thing keeping them from getting out of homelessness. Their free responses were coded by the interviewer as belonging to one of 7 mutually exclusive categories: insufficient income, lack of suitable/adequate housing, lack of job/employment, addiction(s) to alcohol and/or drugs, family or domestic instability, mental health condition, and all other reasons.

A count of chronic health conditions were obtained by asking participants if they had any of the following 9 conditions: diabetes; anemia; high blood pressure; heart disease or stroke; liver problems including hepatitis; arthritis, rheumatism or joint problems; cancer; problem walking, lost limb or other handicap; and HIV infection or AIDS. This classification of chronic conditions was utilized by a national survey of homeless individuals in the United States.[22]

Mental health problem, alcohol problem, and drug problem in the last 30 days were assessed using the Addiction Severity Index (ASI).[23-24] The ASI has been validated with homeless people and has been used in numerous studies, including a nationwide survey of homeless people in the U.S.[25-28] Problems were dichotomized as present or absent based on criteria previously used with homeless populations.[22] These criteria included the classification of participants as having mental health problem if their ASI mental health score was ≥0.25, alcohol problem if their ASI alcohol score was ≥0.17, and drug problem if their ASI drug score was ≥0.10.[22] We used the SF-12 health survey, a health status instrument that has been validated in homeless populations,[29] to generate scores for the physical and mental component subscales.[30] These scores range from 13 to 69 for physical health and 10 to 70 for mental health, standardized to a mean of 50 and standard deviation of 10 in the general population in the United States.[30]

Statistical Analyses

We compared the characteristics of participants by immigrant status using χ2 and ANOVA. We developed regression models to determine if immigrant status was associated with count of chronic conditions (Poisson regression), mental health problems, alcohol problems, and drug problems (logistic regression), and physical and mental component subscale scores (linear regression) after adjustment for age, sex, accompaniment by children, race/ethnicity, education, income, and lifetime years of homelessness. Due to the forced correlation between region of birth and immigrant status, region of birth was not included in the regression models. Analyses were conducted with unweighted data and computed using SAS software (version 9.1, Cary NC).


Of 2,516 individuals screened at homeless shelters and meal programs, 1,189 people were included in the study (Figure 1). In total, 882 (35%) were ineligible because 229 (9%) did not meet our definition of homelessness, 104 (4%) were unable to communicate in English, 54 (2%) were homeless shelter users encountered at meal programs, and 53 (2%) were unable to give informed consent. Because this study was part of a larger study of homeless people's health care utilization, 442 individuals (18%) were excluded because they did not have an Ontario health insurance number. Most of these 442 individuals were refugees, refugee claimants, or recent migrants to the province of Ontario. Of 1,634 eligible individuals, 443 declined to participate. We enrolled 1,191 (73% of those eligible) in the study, of which information on immigrant status was obtained for 1,189 individuals and missing on 2 individuals.

Figure 1
Flow diagram of participant recruitment

Characteristics of the 1,189 homeless study participants are displayed in Table 1. A total of 116 (10%) study participants were recent immigrants, 261 (22%) were non-recent immigrants, and 812 (68%) were Canadian-born individuals. Mean age was 28.0 years for recent immigrants, 39.7 years for non-recent immigrants, and 36.2 years for Canadian-born individuals (p<0.001). Compared to non-recent immigrants and Canadian-born individuals, recent immigrants were more likely to be female, accompanied by dependent children, married, and had a non-caucasian racial status (Table 1). Recent immigrants were also more highly educated and had a somewhat shorter duration of homelessness.

Table 1
Characteristics of study participants

Homeless recent immigrants were unlikely to have alcohol problems, drug problems, and mental health problems (Table 1). Although mental health problems were also less prevalent among recent immigrants (23%) than non-recent immigrants (35%) and Canadian-born individuals (40%), the gradient across the 3 groups was less steep (p=0.002) compared to that for alcohol and drug problems. Recent immigrants were also less likely to have chronic conditions and more likely to have better SF-12 physical health scores compared to non-recent immigrants and Canadian-born individuals (Table 1).

These three groups gave significantly different responses regarding the single most important thing keeping them from getting out of homelessness (p<0.001) (Table 2). Recent immigrants were more likely to report financial reasons (i.e., insufficient income or lack of job/employment) and housing reasons (i.e., lack of suitable/adequate housing). In contrast, recent immigrants were less likely to report mental health conditions or addictions, compared to non-recent immigrants and Canadian-born individuals.

Table 2
Reasons cited by participants as the single most important thing keeping them from getting out of homelessness

Table 3 shows the findings from multivariate regression analyses examining the association between immigrant status and current health problems. In models adjusted for age, sex, accompaniment by dependent children, race/ethnicity, education, income, and lifetime years of homelessness, homeless recent immigrants were significantly less likely to have chronic conditions, mental health problems, alcohol problems, and drug problems compared to homeless non-recent immigrants and homeless Canadian-born individuals. Recent immigrants also had significantly better mental and physical health status. In all models, the health status of non-recent immigrants was not significantly different from that of Canadian-born individuals.

Table 3
Association between immigrant status and health status


This study confirms that a strong “healthy immigrant effect” is found among homeless individuals in Toronto, Canada. Recent immigrants who are homeless are physically and mentally healthier and less likely to suffer from chronic conditions and substance use problems than native-born homeless individuals. Moreover, length of time since immigration is a critical factor, as the health status of homeless individuals who immigrated more than 10 years ago is not significantly different from that of homeless non-immigrants. It has been hypothesized that this phenomenon may arise because immigrants adopt lifestyles and behaviors similar to that of the native-born population.[4, 9]

However, an alternative explanation is that recent immigrants are more vulnerable to becoming homeless with fewer physical and mental health problems which are highly prevalent among native-born individuals who are homeless. Thus, economic and housing factors may be more important in precipitating and prolonging homelessness among recent immigrants. This hypothesis is consistent with participants' self-reported reasons for what was keeping them from getting out of homelessness. Recent immigrants were more likely to report insufficient income, lack of employment, and lack of suitable housing as primary factors, and less likely to report mental health, alcohol use, or drug use. Previous studies have documented that recent immigrants face an initial disadvantage in the labor market, earning wages well below that of the native-born population.[31-34] Recent immigrants also have substantially higher rates of poverty compared to native-born individuals (22% vs. 16% in Canada, and 17% vs. 13% in the United States).[35-36]

These findings have two major implications. First, recent immigrants who become homeless are generally much healthier than other homeless individuals, and they are much less likely to need treatment for substance abuse. Thus, interventions that specifically focus on job skills, training, and employment may be especially advantageous for this group. Second, although homeless recent immigrants have lower levels of mental health problems than other homeless people, their prevalence of mental health problems is still quite high (23%). This finding demonstrates the need for access to culturally appropriate mental health services for recent immigrants who become homeless. Finally, further work is needed to develop strategies to prevent recent immigrants from becoming homeless due to primarily economic reasons.

Strengths and Limitations

This study has several strengths. Our findings provide new insights into the relationship between immigration, homelessness, and health, the intersection of which has been the subject of little previous research. We enrolled a large representative sample of homeless single men, single women, and adults with dependent children in a major North American city, including shelter users and non-shelter users. Rigorous methods were employed to select participants randomly at each site. We also achieved a high response rate, with 73% of eligible individuals successfully recruited.

This study has certain limitations. Our study did not include homeless individuals who used neither shelters nor meal programs, and thus our findings may not be generalizable to this subgroup of homeless persons. Refugees and refugee claimants were excluded from this study, and previous research has found that refugees generally have poorer physical and mental health than other immigrants because of their experiences prior to arrival and the less stringent screening process which they undergo.[37-38] Thus, our study's findings should not be generalized to homeless refugees. In addition, our findings may not be generalizable to undocumented immigrants, who constitute a very small proportion of immigrants in Canada and who were also excluded from this study. Homeless people who were unable to communicate in English were not enrolled in this study; however, these individuals accounted for only 4% of those screened for eligibility. Finally, this cross-sectional study does not control for cohort effects (such as recent immigrants potentially undergoing more rigorous screening than previous cohorts of immigrants).


This study demonstrates that the “healthy immigrant effect” can be generalized to highly disadvantaged and marginalized groups such as the homeless. Moreover, these findings indicate that homeless recent immigrants are a relatively distinct group who are generally healthier and more likely to report economic and housing issues as barriers preventing them from getting out of homelessness than other homeless people. Longitudinal data are needed to better understand the health and housing trajectories of homeless recent immigrants compared to other homeless individuals. Further research is needed to better understand the needs of this subgroup of people experiencing homelessness and to identify effective interventions.


This project was supported by operating grants from the Agency for Healthcare Research and Quality (1 R01 HS014129-01) and the Canadian Institutes of Health Research (MOP-62736), and by an Interdisciplinary Capacity Enhancement grant on Homelessness, Housing, and Health from the Canadian Institutes of Health Research (HOA-80066). The Centre for Research on Inner City Health and the Institute for Clinical Evaluative Sciences gratefully acknowledge the support of the Ontario Ministry of Health and Long-Term Care. Dr. Hwang is the recipient of a New Investigator Award from the Canadian Institutes of Health Research. Dr. Redelmeier is supported by the Canada Research Chair in Medical Decision Sciences. The authors thank Marko Katic, Department of Research Design and Biostatistics, Sunnybrook Health Sciences Centre, for expert programming and analyses.

The funders for this study did not play any role in the study design, in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

The authors also thank the shelters and meal programs that allowed the recruitment of participants and the interviews to be conducted at their sites. The views expressed in this publication are the views of the authors and do not necessarily reflect the views of the Ontario Ministry of Health and Long-Term Care or any of the other above named organizations.


What is already known about this subject

  • Homeless people have much poorer health status than the general population.
  • Immigrants tend to be healthier than their native-born counterparts in the general population (the “healthy immigrant effect”).

What this study adds

  • Compared to other homeless people, homeless recent immigrants have fewer physical and mental health problems and more likely to report economic and housing issues as barriers preventing them from getting out of homelessness.
  • The “healthy immigrant effect” can be generalized to highly marginalized groups such as the homeless.
  • About one-fourth of homeless recent immigrants have had mental health problems in the past 30 days.

Contributors: Chiu, Redelmeier, Tolomiczenko, Kiss, and Hwang contributed to the study concept and design. Hwang originated and supervised the overall study. Chiu oversaw all aspects of the data collection. Chiu, Kiss and Hwang analyzed and interpreted the data. Chiu and Hwang drafted and revised the manuscript critically for important intellectual content. Redelmeier, Tolomiczenko, and Kiss critically revised the manuscript for important intellectual content. Hwang is the guarantor of the paper and accepts full responsibility for the work, the conduct of the study, had access to the data, and controlled the decision to publish. All authors approved the final version of the manuscript to be published.

Licence for Publication: The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive licence (or non-exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd and its Licensees to permit this article to be published in Journal of Epidemiology and Community Health editions and any other BMJPGL products to exploit all subsidiary rights, as set out in our licence

Competing Interests: All authors have no competing interests, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript.


1. Terrazas A, Batalova J, Fan V. Washington, DC: Migration Policy Institute; Oct2007. [22 May 2009]. Frequently requested statistics on immigrants in the United States.
2. Chui T, Tran K, Maheux H. Ottawa: Social and Aboriginal Statistics Division, Statistics Canada; [22 May 2009]. Immigration in Canada: a portrait of the foreign-born population, 2006 Census Findings.
3. Ali JS, McDermott S, Gravel RG. Recent research on immigrant health from Statistics Canada's population surveys. Can J Public Health. 2004;95:19–23. [PubMed]
4. Perez C. Supplement to Health Reports. Vol. 13. Ottawa: Statistics Canada; 2002. [22 May 2009]. Health status and health behaviour among immigrants.
5. Jasso G, Massey DS, Rosenzweig MR, et al. Immigrant health: selectivity and acculturation. In: Anderson NB, Bulatao RA, Cohen B, editors. Critical perspectives on racial and ethnic differences in health in later life. Washington D.C: The National Academic Press; 2004. pp. 227–66.
6. Antecol H, Bedard K. Unhealthy assimilation: why do immigrants converge to American health status levels? Demography. 2006;43:337–60. [PubMed]
7. Dunn JR, Dyck I. Social determinants of health in Canada's immigrant population: results from the National Population Health Survey. Soc Sci Med. 2000;51:1573–93. [PubMed]
8. Singh GK, Siahpush M. Ethnic-Immigrant differentials in health behaviors, morbidity, and cause-specific mortality in the United States: an analysis of two national data bases. Human Biology. 2002;74:83–109. [PubMed]
9. Chen J, Ng E, Wilkins R. The health of Canada's immigrants in 1995-95. Health Rep. 1996;7:33–45. [PubMed]
10. Ali J. Supplement to Health Reports. Vol. 13. Ottawa: Statistics Canada; 2002. [22 May 2009]. Mental health of Canada's immigrants.
11. Burnam MA, Hough RL, Karno M, et al. Acculturation and lifetime prevalence of psychiatric disorders among Mexican-Americans in Los Angeles. J Health Soc Behav. 1987;28:89–102. [PubMed]
12. Ortega AN, Rosenheck R, Alegria M, et al. Acculturation and the lifetime risk of psychiatric and substance use disorders among Hispanics. J Nerv Ment Dis. 2000;530:74–96. [PubMed]
13. Vega WA, Kolody B, Aguilar-Gaxiola S, et al. Lifetime prevalence of SDM-III-R psychiatric disorders among urban and rural Mexican Americans in California. Arch Gen Psychiatry. 1998;55:771–8. [PubMed]
14. Breslau J, Auilar-Gaxiola S, Borges G, et al. Risk for psychiatric disorder among immigrants and their US-born descendants: evidence from the National Comorbidity Survey Replication. J Nerv and Ment Dis. 2007;195:189–95. [PMC free article] [PubMed]
15. Chan S, Hiebert D, D'Addario S, et al. The profile of absolute and relative homelessness among immigrants, refugees, and refugee claimants in the GVRD: Final Report. Vancouver, BC: MOSAIC; May2005. [22 May 2009].
16. Fiedler R, Schuurman N, Hyndman J. Hidden homelessness: an indicator-based approach examining the geographies of recent immigrants at-risk of homelessness in Greater Vancouver. Cities. 2006;23:205–16.
17. Ottawa: Statistics Canada, Office of Economic Policy, Labour and Demographic Analysis Branch; [22 May 2009]. 2006 Census Highlights, Fact Sheet 7.
18. Toronto: City of Toronto; Apr2006. [22 May 2009]. 2006 Street Needs Assessment: Results and Findings.
19. Toronto: City of Toronto; [22 May 2009]. Toronto Report Card on Housing and Homelessness 2003.
20. Hwang SW, Chiu S, Kiss A, et al. Use of meal programs and shelters by homeless people in Toronto [abstract] J Urban Health. 2005;82:ii46.
21. Statistics Canada; Apr2002. [22 May 2009]. Ethnic Diversity Survey Questionnaire.
22. Homelessness: programs and the people they serve. Washington, DC: Interagency Council on the Homeless; 1999. Findings of the National Survey of Homeless Assistance Providers and Clients; pp. 6-2–6-3.
23. McGahan PL, Griffith JA, Parente R, et al. Addiction Severity Index: Composite Scores Manual. Philadelphia, PA: The University of Pennsylvania/Veterans Administration Centre for Studies of Addiction; [22 May 2009].
24. McLellan AT, Kushner H, Metzger D, et al. The fifth edition of the Addiction Severity Index. J Subst Abuse Treat. 1992;9:199–213. [PubMed]
25. Zanis DA, McLellan AT, Canaan RA, et al. Reliability and validity of the Addiction Severity Index with a homeless sample. J Subst Abuse Treat. 1994;11:541–8. [PubMed]
26. Joyner LM, Wright JD, Devine JA. Reliability and validity of the Addiction Severity Index among homeless substance misusers. Subst Use Misuse. 1996;31:729–51. [PubMed]
27. Drake RE, McHugo GJ, Biesanz JC. The test-retest reliability of standardized instruments among homeless persons with substance use disorders. J Stud Alcohol. 1995;56:161–7. [PubMed]
28. Burt M, Aron LY, Lee E. Helping America's Homeless. Washington DC: The Urban Institute Press; 2001. pp. 100–2.
29. Larson CO. Use of the SF-12 Instrument for Measuring the Health of Homeless Persons. Health Serv Res. 2002;37:733–49. [PMC free article] [PubMed]
30. Ware JE, Kosinski M, Keller SD. SF-12: How to Score the SF-12 Physical and Mental Health Summary Scales. 2nd. Boston, MA: The Health Institute, New England Medical Center; 1995. pp. 21–4.
31. Chiswick B. The Effect of Americanization on the earnings of foreign-born men. J Polit Econ. 1978;86:897–921.
32. Grant M. Evidence of new immigrant assimilation in Canada. Can J Econ. 1999;32:930–55.
33. Pendakur K, Pendakur R. Research on Immigration and Integration in the Metropolis (RIIM) Working Paper Series #96-03. Vancouver, BC: 1996. The Colour of Money; pp. 1–27.
34. LaLonde RJ, Topel RH. Immigrants in the American labor market: quality, assimilation and distributional effects. Am Econ Rev. 1991;81:297–302. [PubMed]
35. Lee K. Urban Poverty in Canada: A Statistical Profile. Ottawa: Canadian Council on Social Development; 2000. [22 May 2009]. Groups vulnerable to poverty in CMSs and CSDs.
36. DeNavas-Watt C, Proctor BD, Smith JC. US Income, Poverty, and Health Insurance Coverage in the United States. Washington, DC: U.S. Census Bureau; Aug2008. [22 May 2009].
37. Kinnon D. Canadian Research on Immigration and Health. Ottawa: Health Canada; 1999. [22 May 2009].
38. Newbold B. The short-term health of Canada's new immigrant arrivals: evidence from the LSIC. Ethnicity Health. 2009 Mar 4; doi: 10.1080/13557850802609956. Published Online First. [PubMed] [Cross Ref]