REVISIÓN

The social determinants of health of the child-adolescent immigration and its influence on the nutritional status: systematic review

Los determinantes sociales de la inmigración infanto-juvenil y su influencia sobre el estado nutricional: revisión sistemática

Kamila Cheikh Moussa³, Javier Sanz-Valero^3,4 and Carmina Wanden-Berghe^1,2

¹Department of Pharmacy, CEU Cardenal Herrera University, Elche.
²Home Care Unit, General University Hospital of Alicante, Alicante. ]]> ³Department of Public Health and History of Science, Miguel Hernandez University, Elche.
⁴Department of Public Health and History of Science, University of Alicante, Alicante. Spain.

Correspondence

ABSTRACT

Objective: to review the social determinants of health more characteristic of the child and adolescents of immigrants, by reviewing the literature and assess its effect on nutritional status.
Methods: a systematic review was performed using Medical Subject Headings (MeSH) in PubMed (Medline) and The Cochrane Library, in order to identify undetected studies; articles bibliographic lists were examined. The final election was done according to inclusion and exclusion criteria. No restrictions on sex and ethnicity of the participants. STROBE checkpoints were used for an information and methodological quality control. As Social Determinants of Health (SDH); social, demographic and economic conditions were considered for the study of their effect on the nutritional status.
Results: from 31 identified articles 18 are included in this study, 17(94,4%) had a good or excellent quality. Hispanic and African were the most studied ethnicities; birth place and parent's residence period were used for generational classification. Alimentary culture and linguistic isolation of the first generation have a protective effect preventing from overweight and obesity risk while it decrease in second and third generation due to the experienced acculturation process equalizing their weight gain to natives; which prevalence is higher among Hispanics. No relation was found for nutritional status differences between sexes neither alimentary aids protective effect hypothesis was confirmed.
Conclusions: the SDH with greater influence on child-adolescent immigrants were the socio-demographic conditions; among them: residence period distinguish the three identified generations while linguistic barrier and ethnic background are truly influential on the biological response to the experimented change caused by the acculturation process, establishing differences in the nutritional status.

RESUMEN

Objetivo: revisar los determinantes sociales de la salud (DSS) más característicos de la población infantil y juvenil de inmigrantes, mediante revisión de la literatura científica y evaluar su efecto sobre el estado nutricional.
Métodos: Se realizó una revisión sistemática utilizando los Medical Subject Headings (MeSH) en PubMed (Medline) y The Cochrane Library, con el fin de identificar los estudios no detectados; se examinaron las listas de artículos bibliográficos. La elección final se hizo de acuerdo con los criterios de inclusión y exclusión. No hubo restricciones sobre el sexo y el origen étnico de los participantes. Se utilizaron los puntos de verificación de la guía STROBE para un control de la información y la calidad metodológica. Como Determinantes Sociales de la Salud (DSS); se consideraron las condiciones sociales, demográficas y económicas para el estudio de su efecto sobre el estado nutricional.
Resultados: Fueron identificados 31 artículos de los que se incluyó un total de 18 estudios, 17 (94,4%) tuvieron una buena o excelente calidad. Las etnias más estudiadas fueron la Hispana y afroamericana; para la clasificación generacional se utilizaron el lugar de nacimiento y tiempo de residencia de los padres. La cultura alimentaria y el aislamiento lingüístico de la primera generación tienen un efecto protector en la prevención de riesgo de sobrepeso y obesidad, mientras que disminuye en la segunda y tercera generación debido al proceso de aculturación experimentado igualando su aumento de peso a los nativos; la prevalencia más alta fue entre los hispanos. No se encontró relación sobre las diferencias del estado nutricional entre los sexos ni se confirmó la hipótesis del efecto protector de las ayudas alimentarias.
Conclusiones: los DSS con mayor influencia sobre la población joven inmigrante son las condiciones socio-demográficas; entre ellos: el tiempo de residencia distingue las tres generaciones identificadas mientras que la barrera lingüística y el origen étnico son los verdaderamente influyentes en la respuesta biológica al cambio experimentado causado por el proceso de aculturación, estableciendo así diferencias en el estado nutricional.

Palabras clave: Emigrantes e inmigrantes. Estado nutricional. Sobrepeso. Cambios en el peso corporal.

Abbreviations
MEDLINE: Medlars International Literature Online.
MeSH: Medical Subject Headings. ]]> STROBE: Strengthening the Reporting of Observational Studies in Epidemiology.
ECLS: Early Childhood Longitudinal Study.
U.S.: Original of The United States of America.

Introduction

The transition years between childhood and adolescence marks a critical socialization period in which the acquisition of food habits is defined by socio-economic, cultural factors and the environment^1-3.In the immigrant population this relationship, according Alba & Nee⁴, was described from a perspective through three distinctions of the assimilation theory: sociocultural, negative and segmented.

Thus, the study of food habits in immigrants and the related changes in body weight took interest from a generational approach (child and adolescent), the differences between the two generations are considered result of the decreased effect of ethnicity on conditioning factors due to the place of socialization of each generación^{5, 6}.

In this sense, this socialization process is established by the structural determinants and living conditions, these constitute the social determinants of health. Yet at the same time are the causes of the majority of health inequalities⁷. Such inequalities, as child poverty, which affects 4 out of each 5 persons, and passing from one generation to another, are major obstacles in improving population health and reducing inequalities⁸.

At present, the figure of 1000 million people are in a "migrant" situation makes their state of health a priority of Global Public Health⁹. (Fig. 1)

Hence, in relation to the above, the objective of this study is to review the social determinants of health more characteristic of the child and adolescents of immigrants, by reviewing the literature and assess its effect on nutritional status.

Materials and Methods

Design

Descriptive study of the articles retrieved using systematic technique.

Sources of data extraction

All data were obtained from direct consultation and access via Internet to the scientific literature contained in the database Medlars International Literature Online (MEDLINE), via PubMed and The Cochrane Library.

Data processing

We studied the articles published in any country and language.

For the recovery of evidence were used Medical Subject Headings (MeSH) developed by the U.S. National Library of Medicine. Search equations were developed for its use in the MEDLINE database via PubMed, using Boolean connectors, and in The Cochrane Library proceeding in the same way.

From the study of the Thesaurus the following descriptors were used "Emigrants and Immigrants", "Socioeconomic Factors, Cultural Characteristics, Social Class", "Nutritional Status, Overweight, Obesity, Body Mass Index, Body Weight Changes" and "Cohort Studies". "Humans" was used as a limit. Also limiting to the last 7 years (2005-2012), as the period of obsolescence (half period of Burton Kebler) established for publications in the field of health science¹⁰ and nutrition¹¹.

The final election of the works was done according to the fulfillment of the inclusion and exclusion criteria.

Inclusion criteria: The accepted articles were those with longitudinal design of Cohorts type whose study population consisted of immigrants between 2-18 years of age. We selected original articles published in peer journals, full text of which was recovered.

Exclusion criteria: Articles of different design which comprised pathology cases, pregnancies and only adults.

Additionally, as a secondary search and to reduce potential publication bias, we examined the bibliographic list of articles that were selected in the main quest, in order to identify undetected studies in bibliographic databases.

For quality control of information were used the 22 checkpoints of the guide "Strengthening the Reporting of Observational Studies in Epidemiology" (STROBE) based on the 4 items (8, 13 to 15 checkpoints) specific for the methodological quality of cohort studies¹².

To determine the pertinence of the articles were assessed independently by two of the authors of this review (K C-M and J S-V). To give as valid the election of the articles selected for the review it was established the assessment of the concordance between these two authors (kappa index) which should be greater than 0.60 (strength of agreement was good or very good). As long as this condition is fulfilled, any discrepancies are solved by consulting the third author (C W-B) and subsequent consensus among all authors.

Data extraction

Studies were grouped according to study the variables in order to systematize and facilitate the understanding of the results of all reviewed articles. There were no restrictions on sex and ethnicity of the participants. And were summarized in a table, codifying: authors, year of publication, population under study, ethnicity, immigrant generation, carried intervention, follow-up period, where the intervention took place and the main conclusions indicated in the reviewed articles.

Social determinants of health that are considered to assess its scope on the nutritional status were those of social and demographic kind (ethnicity, race, country of birth, number of years resided in the host country, number of siblings, parents' educational level, linguistic and social integration) as well as the economics (occupation of the primary caregiver, family income and the type of school).

Results

A total of 14 articles were recovered from MEDLINE while not getting results from The Cochrane Library database. From the bibliographic list of the reviewed articles 18 works were identified.

Five works didn't meet the inclusion criteria by considering a different issue. Nine studies which population wasn't immigrant children and adolescent were eliminated or their principal objective wasn't the study of the effect on population's nutritional status but the prevention of diseases (cardiovascular diseases, diabetes, cancer, etc.). Thus, after applying the inclusion and exclusion criteria, 18 studies were selected^13-30; see table I.

The agreement about the quality of the studies between the authors was 100%. Of the selected articles 10 (55,5%)^{13-15, 17, 19, 24-26, 29} considered all the quality variables while 8 (44,4%) studies^{16, 18, 20-23, 27, 30} included 90-95% of them. Despite this, 17 (94,4%) articles^13-29 had a good or excellent quality; see Table II.

Of the 18 interventions, 12 (66,6%)^{13, 15-17, 19, 21-24, 27-29} took place in United States of America while the 6 (33,3%) left were in Canada^{14, 30}, Australia^{20, 26}, Austria¹⁸ and Denamark²⁵. The period of study for 17 (94%) articles was between 4 and 6 years, and 2 years for the rest²⁵. The places where the interventions have been carried out were mainly the family residence^{14-17, 20-22, 26-28} and/or educational centers^{13, 18,30}.

The most used instruments for the intervention were the anthropometric measures^{13-17 ,21, 23-27, 30}, the surveys^{14, 16, 17, 19, 21, 22, 27, 28}, the questionnaires on socioeconomic status^{15, 16, 25} and demographic characteristics^{13, 21, 23, 27-30} (a detailed description of these and of the principal objective of each study are provided in Table III).

Varied information was found about the subjected population, the most studied ethnicity background was the Hispanic^{14, 17, 23, 27, 30} followed by the African^{16, 22, 28, 29}, the place of birth was mainly used for the generational classification^{13, 17, 18, 22, 24-28, 30}, followed by the years of residence of the parents^{20, 21, 23, 29}. The intervention with the largest number of individuals had n=20745²⁸ and the smallest had n=210 persons¹⁴.

Most studies^{13, 17, 18, 20-22 24, 26-30} show that the coexisting social conditions between the three identified generations produce differences in their nutritional status, highlighting the protective effect of the immigrant status of the first generation, characterized by the alimentary culture and the linguistic isolation, which protect them from the risk of overweight or obesity^{17, 21, 28-30} while in the case of the second and third generation their weight gain get equalized to the native population due to the adaptation or acculturation process^{13, 17, 21, 28-30}.

The prevalence of overweight and later obesity was higher in Hispanic individuals compared to the native population of the studied country^{17, 19, 22, 28}. No relation was found in the study of nutritional status differences between sexes. Neither was confirmed the hypothesis that the access to alimentary aids protects the individuals from malnutrition or overweight/obesity.

Discussion

As has been observed, the most part of the studies took place in The United States of America probably due to the immigration population of this country which comprises 40.377.757 persons (Data was obtained from the emigration database of The Migration Policy Institute of USA, http://www.migrationinformation.org/datahub/countrydata/country.cfm) and because historically has been under study (Early Childhood Longitudinal Study, ECLS Study - http://nces.ed.gov/ecls/).

The use of the familiar residence as the principal place of intervention is due to the easy access to the family data from mothers. Also, the school center was an optimal place for collecting information from children^{26, 30, 31}. The use of the surveys-in-home provided continuity for information collection to define the ethnic profile and the social status, as well as the questionnaires referred to alimentation, origin country, familiar characteristics and incomes.

Some U.S. studies^{13, 16, 19, 21, 22, 28, 29} observed several ethnic origins being the Hispanic the most studied due to the heterogeneity within this ethnic group and to its massive immigration to the host country^{24, 27}.

The exclusive election of cohort studies could be considered a limitation but its design generates a large amount of inputs due to its long-time term in comparison to the observational studies of cross-sectional and case-control design¹². Another possible limitation of this revision is the exclusion of studies about adult population for which there is a larger number of articles. Nevertheless, this age range is considered the stage of "consequences" because before reaching it is in the childhood and teenage when there is an increasing susceptibility to environmental modulator factors (socioeconomics and demographics) producing changes that are transferred to adulthood in worse outcomes²⁸.

Although no revisions were found that specifically address about the effect of the social determinants on the nutritional status of the young generations of immigrants, Misra, et al.³¹ focuses on the study of obesity prevalence and metabolic syndrome in socially vulnerable persons and migrants from rural areas to cities of a same territory and the development of cardiovascular diseases and diabetes mellitus type II. Another article, included in this study, Renzaho, et al.²⁶, addresses the relation between the nutritional status in childhood and the ethnicity in a representative sample of children aged 5 years from different cultural and ethnic backgrounds, finding the same results as Suminski, et al¹⁵ and other authors^{26, 27, 29}, concluding that there is a higher probability of body weight changes for Hispanics who belong to a family with a high proportion of overweight/obesity and there is less weight gain among girls of any ethnicity.

The social determinants of health with greater influence on the child-adolescent immigrants were the socio-demographic conditions; among them: the period of residence distinguish the three identified generations^{13, 20} within the studies while the linguistic barrier and the ethnic background are truly influential on the biological response to the experimented change caused by the acculturation process, establishing differences in the nutritional status²⁶.

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Correspondence:
Javier Sanz-Valero.
Department of Public Health and History of Science.
Miguel Hernandez University.
Elche. Spain.
E-mail: jsanz@umh.es