Abstract
Limited studies have evaluated the link between acculturation and health outcomes of within-country migrants. The objective of this study was to evaluate whether well-known acculturation surrogates were associated with obesity among Peruvian rural-to-urban migrants. We performed a cross sectional survey, the PERU MIGRANT study, using single-stage random sampling. Evaluation included weight, height, and waist circumference (WC) as well as acculturation surrogates. Obesity was assessed using body mass index (BMI) and WC. Length of residence, age at migration, language proficiency and language preferences (Spanish or Quechua) were assessed in logistic regression models to calculate odd ratios (OR) and 95% confidence intervals (CI) adjusting for potential confounders. A total of 589 rural-to-urban migrants were enrolled. The mean age was 47.8 (SD: 11.7, range: 30-92) and 280 (47.5%) were males. Obesity prevalence assessed by BMI was 30.4% among women and 10.7% among men (p<0.001), whereas abdominal obesity assessed by WC was 29.1% among women and 19.1% among men (p<0.01). Obesity was associated with older age at first migration, language speaking proficiency and language preferences. The association between obesity and acculturation surrogates is variable in this population. Thus, acculturation per se can explore positive channels associated with better health outcomes. The patterns shown in this report suggest a more complex association for these factors.
Keywords: acculturation, obesity, adults, body mass index, waist circumference
INTRODUCTION
Obesity is one of the main risk factors associated with cardiovascular disease (CVD), including all-cause and CVD mortality (1). In addition, many recognized CVD risk factors such as obesity, physical inactivity, diabetes, and hypertension are on the rise in all regions, including low- and middle-income countries (2, 3).
Migrant populations can be more affected by unhealthy practices due to disparities in health and access to care (4). Besides, when more acculturated, migrants tend to increase their risk of obesity and other chronic health conditions, leading to a decline in their health status advantages (5, 6). Most of the studies, however, have generally focused on behaviors and disease conditions among migrants residing in the United States.
Acculturation, a process of adaptation and exchange of behavior patterns resulting when groups of human beings with different cultures come into continuous contact (7), has been described in the literature using several surrogates, including length of residence (8), age at migration (9), language use and proficiency (10, 11), and others (12). However, limited reports have assessed the association between acculturation and obesity among rural-to-urban migrants. Thus, it is important to evaluate it in the current context of increased urbanization in low- and middle-income countries.
The objective of this study was to evaluate acculturation using length of residence, age at first migration, self-reported language proficiency, and language preference, and its association with obesity among Peruvian rural-to-urban migrants.
METHODS AND PROCEDURES
Study design, setting and participants
A cross sectional survey, the PERU MIGRANT study (13), was performed using a single-stage random sampling and involving migrants from rural to urban areas in Peru. Potential participants, born in the rural setting of Ayacucho, who migrated to, and were currently living in the urban setting of Lima, were asked to participate. The area called “Las Pampas de San Juan de Miraflores” was the setting where this study was carried out. The sampling frame for this migrant group was the local census performed in 2000, updated in 2006, to identify all those who stated they had been born in the department of Ayacucho and were currently living in Lima. A total of 589 (82.7%) of 712 enrolled participants completed the study.
Data collection
Community health workers were trained to recruit participants and conduct interviews using validated questionnaires. Questions were asked in Spanish or Quechua languages by bilingual health workers depending on the participant’s preference. Socio-demographic, migration, alcohol use, smoking, and acculturation variables were collected. Workers were also trained to obtain clinical measurements using standardized methods and calibrated tools. Measurements included were height, weight, and waist circumference (WC). Total height was measured to the nearest 0.1 cm using a stadiometer, whereas weight was obtained from the individual wearing light clothes to the nearest 0.05 kg using a SECA 940 electronic scale. WC was measured in triplicate at the midpoint between the lower rib and the iliac crest in the horizontal plane while the participant was standing.
Variables definition
Obesity was the outcome of interest. Two different variables were used to assess obesity. Firstly, body mass index (BMI) categorized using accepted guidelines (BMI ≥ 30 kg/m2) (14). Secondly, WC with specific cut-offs (WC ≥97 cm for men and ≥94 cm for women) according to the Latin-American Consortium of Studies in Obesity (LASO) (15). Exposure variables were length of residence in urban areas evaluated in two categories (< 30 and ≥ 30 years), age at first migration divided into three categories (< 10, 10–17, and ≥ 18 years), and language proficiency based on the self-report of how well participants speak Spanish. Possible responses were categorized into two groups for analysis: “very well” and “pretty well” were grouped in one category (acculturated), whereas “not too well” and “not at all” were grouped in the other (not acculturated). Language preference for listening was evaluated by the question “If available on the radio, what language would you prefer to listen to?” Possible responses were categorized into two groups: “Only Spanish” and “Quechua or Spanish/Quechua”. A Spanish version of the questionnaire is available at http://www.biomedcentral.com/content/supplementary/1471-2261-9-23-S1.doc (13).
Statistical analysis
Statistical analysis was performed using STATA 10 for Windows (STATA Corporation, College Station, Texas, US). Initially, a brief description of the socio-demographic, acculturation surrogates and health-related variables was performed according to obesity. A multi-deprivation index was also considered to evaluate socio-economic status.
Categorized variables were assessed in logistic regression models to calculate adjusted odd ratios (OR) and 95% CI. Potential confounders used in the adjusted model were age, gender, education level, socio-economic status using a deprivation index, alcohol use, smoking status, and physical activity assessed by the metabolic equivalent task (MET) score.
Ethical issues
Ethical approval for this study was obtained from IRBs at Universidad Peruana Cayetano Heredia in Peru and London School of Hygiene and Tropical Medicine in the UK.
RESULTS
A total of 589 rural-to-urban migrants were included in the analysis. The mean age was 47.8 years (SD: 11.7, range: 30–92) and 280 (47.5%) were males. Overall, obesity prevalence assessed by BMI was 30.4% among women and 10.7% among men (p<0.001). On the other hand, abdominal obesity assessed by WC was 29.1% among women and 19.1% among men (p<0.01). A description of characteristics and health-related variables are shown in Table 1. Table 2 shows results adjusted for several potential confounders. Obesity, assessed using BMI, was associated with age at first migration (p = 0.03), particularly for those migrating at ≥18 years, Spanish speaking ability (P = 0.03), and language preferences (P = 0.04). Abdominal obesity, assessed using Latin-American Consortium of Studies in Obesity cut-offs for WC, was associated with age at first migration (P = 0.04) and language preferences (P = 0.01).
Table 1. Distribution of socio-demographic and health-related variables according to length of residence and age at first migration.
| Variables | General obesity a | Abdominal obesity a, b | ||
|---|---|---|---|---|
|
| ||||
| BMI < 30 (N = 465) |
BMI ≥ 30 (N = 124) |
No (N = 444) |
Yes (N = 143) |
|
| Age | ||||
| Mean (SD) | 47.7 (12.1) | 48.2 (9.8) | 46.9 (11.9) | 50.5 (10.5) |
| Gender | ||||
| Female (%) | 215 (46.2%) | 94 (75.8%) | 219 (49.3%) | 90 (62.9%) |
| Education level | ||||
| None/some elementary school (%) | 130 (28.0) | 53 (42.7) | 122 (27.6%) | 60 (42.0%) |
| Complete elementary school (%) | 75 (16.2) | 24 (19.4) | 71 (16.0%) | 28 (19.6%) |
| Some high school (%) | 259 (55.8) | 47 (37.9) | 250 (56.4%) | 55 (38.5%) |
| Multi-deprivation index | ||||
| Yes (%) | 78 (16.8%) | 29 (23.4%) | 71 (16.0%) | 36 (25.2%) |
| Current smoking | ||||
| Yes (%) | 49 (10.5%) | 10 (8.1%) | 48 (10.8%) | 11 (7.7%) |
| Alcohol use: heavy drinker | ||||
| Yes | 38 (8.2%) | 10 (8.1%) | 35 (7.9%) | 13 (9.1%) |
| Physical activity | ||||
| Moderate/high physical activity | 329 (71.7%) | 80 (65.0%) | 313 (71.5%) | 95 (66.9%) |
| Low physical activity | 130 (28.3%) | 43 (35.0%) | 125 (28.5%) | 47 (33.1%) |
| Length of residence | ||||
| < 30 years | 207 (46.5%) | 49 (43.0%) | 209 (48.9%) | 47 (36.2%) |
| ≥ 30 years | 238 (53.5%) | 65 (57.0%) | 218 (51.1%) | 83 (63.8%) |
| Age at first migration | ||||
| < 10 years old | 112 (24.3%) | 20 (16.1%) | 112 (25.4%) | 20 (14.1%) |
| 10 – 17 years old | 256 (55.5%) | 73 (58.9%) | 243 (55.1%) | 85 (59.9%) |
| ≥ 18 years old | 93 (20.2%) | 31 (25.0%) | 86 (19.5%) | 37 (26.0%) |
| How well speak Spanish | ||||
| Not too well / no at all | 124 (27.0%) | 31 (25.6%) | 114 (26.0%) | 41 (29.3%) |
| Very well / pretty well | 336 (73.0%) | 90 (74.4%) | 325 (74.0%) | 99 (70.7%) |
| Language preferences for listening | ||||
| Quechua or Spanish | 340 (74.2%) | 101 (84.2%) | 320 (73.4%) | 120 (85.7%) |
| Only Spanish | 118 (25.8%) | 19 (15.8%) | 116 (26.6%) | 20 (14.3%) |
Results may not add due to missing values
Calculated according to cut-offs of LASO study
Table 2. Association between acculturation and obesity assessed as BMI and waist circumference: adjusted odds ratios (95% CI).
| BMI ≥ 30 kg/m2 Adjusted model a |
LASO criteria (WC) Adjusted model a |
|
|---|---|---|
| Length of residence | ||
| < 30 years | 1 (Ref) | 1 (Ref) |
| ≥ 30 years | 1.20 (0.72-1.99) | 1.47 (0.91-2.37) |
| Age at first migration | ||
| < 10 years old | 1 (Ref) | 1 (Ref) |
| 10 to 17 years old | 1.75 (0.99-3.12) | 1.79 (1.03-3.12) |
| ≥ 18 years old | 2.15 (1.07-4.33) | 1.97 (1.02-3.79) |
| How well speak Spanish | ||
| Not too well / no at all | 1 (Ref) | 1 (Ref) |
| Very well / pretty well | 1.77 (1.05-2.99) | 1.27 (0.79-2.05) |
| Language preferences for listening | ||
| Quechua or Spanish | 1 (Ref) | 1 (Ref) |
| Only Spanish | 0.56 (0.32-0.98) | 0.51 (0.30-0.87) |
Adjusted by age, sex, education level, deprivation index, alcohol consumption, smoking status and physical activity
DISCUSSION
The objective of this study was to evaluate the association between several acculturation surrogates and obesity, a well-known risk factor for CVD. Among Peruvian rural-to-urban migrants, we demonstrated that obesity was associated with age at first migration, language proficiency, and language preferences.
Reasons for migration depend upon life phase (16). Those migrating before adolescence travel with their families who migrate to improve their economic status, having better opportunities for education, but they are also more likely to become more acculturated, which has a greater impact on their behavior and consequently on their health (17). In our report, however, the odds of obesity, using both markers separately, was greater at older age at migration. These contradictory findings could be explained by environmental exposures, including nutrition patterns. Diet among population from Andean regions is based on carbohydrates, which might influence migrant’s health; however, this hypothesis requires confirmation. Previous reports described the effect of acculturation on obesity among migrants, who mostly migrated to developed countries for economic reasons (6, 18, 19). Mass-migration in Peru, however, largely took place for the purpose of escaping from terrorism rather than for economic reasons (20). In that sense, this population was not simply a small self-selected group. It is therefore essential to use other study designs for appropriate analysis of the impact of migration on health among this type of population.
Language has been also used as acculturation surrogate in previous reports, including fluency and preferences in social interactions (10, 11). In our context, Quechua is the usual language in Andean rural areas, while Spanish is the common language in urban areas. Many studies have previously reported the association between language and over-weight related behaviors (5), and health practices (21). In our study, we show an association between obesity and self-reported ability to speak Spanish. Thus, greater acculturation, measured as self-reported fluency in Spanish, was a risk factor for obesity after adjusting for potential confounders. This observation follows the same direction as that observed in Latino populations living in the US where better language (English) fluency is a sign of greater acculturation (8, 19, 22).
Preference for listening Spanish, however, was associated with lower odds of obesity. Although our model was adjusted for potential confounders, we found opposite results compared to language proficiency. This study therefore expands on the available literature suggesting that measures of language proficiency and preference, although related, do not assess acculturation in the same way. As recently reported, language preference (for listening in this case) tends to reflect participants’ underlying cultural values, but also social networks, political ideology, and social identity (23). Thus, the interpretation of questions regarding language preference might change depending on the participants’ context and background. On the other hand, language proficiency may directly influence access to health care and broader social determinants of disease (23). Language preference might be an indicator of migrants’ adoption of unhealthy lifestyles, a marker of acceptance of health-promoting practices, or a proxy for language proficiency and barriers to health access (24). In this study, we believe that language preference for listening in Spanish amongst within-country migrants – assessed by ideal language for listening to radio programs – could either be a marker of enhanced attitudes or access towards health promoting practices. However, complex studies are needed to improve our understanding of the mechanisms and interactions between variables. Longer residence in urban environment was not associated with obesity as having been reported in previous studies (6, 18).
Strengths of this study include the use of a well-defined within-country migrant population, the assessment of several surrogates of acculturation on obesity, as well as the use of two different obesity indicators. Both obesity indicators have been independently associated with CVD and mortality. While BMI relates to overall obesity, WC assesses mainly abdominal obesity and mainly the amount of visceral fat (25). However, cut-offs derived from other populations for use in our population have been questioned. In this manuscript, using proposed WC cut-offs for our population, we could reach similar results using BMI. This study, however, has some limitations. First, the sample size was small compared to previous studies, which prevents a complete evaluation of the association between acculturation and obesity. Second, although age at first migration and language preference were associated with obesity, dietary patterns were not measured. This could explain the inverse association found in this study compared to other studies (9, 16). Finally, acculturation is a complex process, comprising multiple dimensions, and cannot be completely evaluated through simple variables or cross sectional studies. Although we used previously reported variables associated with chronic diseases and health-related conditions; further studies are needed to confirm our findings.
In conclusion, acculturation is a process affecting rural-to-urban migrants. Length of residence, age at migration, language proficiency, and language preferences are easily evaluable surrogates that can be used to assess the migration and health association among within-country migrants. While traditionally acculturation surrogates have been described to be associated with negative health outcomes, largely interpreted by the adoption of negative lifestyle risk factors, in this paper we report some findings in the opposite direction. That is, acculturation considering language preference for listening in Spanish - the hosting language - showed lower odds of obesity. This reflects that acculturation per se can also explore positive channels associated with better health outcomes. Different approaches and more complex studies with greater sample sizes are needed to more fully understand mechanisms of unhealthy behaviors in low- and middle-income countries.
ACKNOWLEDGEMENTS
Our special gratitude to various colleagues at Universidad Peruana Cayetano Heredia and A.B. PRISMA in Lima, Peru and several others in the UK, as well as to the staff and the team of fieldworkers that contributed to different parts of this study.
This work was funded through by a Wellcome Trust Masters Research Training Fellowship and a Wellcome Trust PhD Studentship to J. Jaime Miranda (GR074833MA). Liam Smeeth is supported by a Wellcome Trust Senior Research Fellowship in Clinical Science. The CRONICAS Center of Excellence in Chronic Diseases at UPCH is funded by the National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health, Department of Health and Human Services, under contract N° HHSN268200900033C.
Footnotes
DISCLOSURE STATEMENT The authors declare that they have no competing interests.
Advance online publication; http://www.nature.com/oby/journal/vaop/ncurrent/abs/oby201092a.html
REFERENCES
- 1.Lindsted KD, Singh PN. Body mass and 26-year risk of mortality among women who never smoked: findings from the Adventist Mortality Study. Am J Epidemiol. 1997 Jul 1;146(1):1–11. doi: 10.1093/oxfordjournals.aje.a009185. [DOI] [PubMed] [Google Scholar]
- 2.Vanuzzo D, Pilotto L, Mirolo R, Pirelli S. Cardiovascular risk and cardiometabolic risk: an epidemiological evaluation. G Ital Cardiol (Rome) 2008 Apr;9(4 Suppl 1):6S–17S. [PubMed] [Google Scholar]
- 3.Lopez AD, Mathers CD, Ezzati M, Jamison DT, Murray CJ. Global and regional burden of disease and risk factors, 2001: systematic analysis of population health data. Lancet. 2006 May 27;367(9524):1747–57. doi: 10.1016/S0140-6736(06)68770-9. [DOI] [PubMed] [Google Scholar]
- 4.Koya DL, Egede LE. Association between length of residence and cardiovascular disease risk factors among an ethnically diverse group of United States immigrants. J Gen Intern Med. 2007 Jun;22(6):841–6. doi: 10.1007/s11606-007-0163-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Gordon-Larsen P, Harris KM, Ward DS, Popkin BM. Acculturation and overweight-related behaviors among Hispanic immigrants to the US: the National Longitudinal Study of Adolescent Health. Soc Sci Med. 2003 Dec;57(11):2023–34. doi: 10.1016/s0277-9536(03)00072-8. [DOI] [PubMed] [Google Scholar]
- 6.Kaplan MS, Huguet N, Newsom JT, McFarland BH. The association between length of residence and obesity among Hispanic immigrants. Am J Prev Med. 2004 Nov;27(4):323–6. doi: 10.1016/j.amepre.2004.07.005. [DOI] [PubMed] [Google Scholar]
- 7.Kottak CP. In: Windows on Humanity: A Concise Introduction of Anthropology. Hill M, editor. Phillip A. Butcher; New York: 2005. [Google Scholar]
- 8.Moran A, Roux AV, Jackson SA, Kramer H, Manolio TA, Shrager S, et al. Acculturation is associated with hypertension in a multiethnic sample. Am J Hypertens. 2007 Apr;20(4):354–63. doi: 10.1016/j.amjhyper.2006.09.025. [DOI] [PubMed] [Google Scholar]
- 9.Colon-Lopez V, Haan MN, Aiello AE, Ghosh D. The effect of age at migration on cardiovascular mortality among elderly Mexican immigrants. Ann Epidemiol. 2009 Jan;19(1):8–14. doi: 10.1016/j.annepidem.2008.08.010. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Deyo RA, Diehl AK, Hazuda H, Stern MP. A simple language-based acculturation scale for Mexican Americans: validation and application to health care research. Am J Public Health. 1985 Jan;75(1):51–5. doi: 10.2105/ajph.75.1.51. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Eamranond PP, Legedza AT, Diez-Roux AV, Kandula NR, Palmas W, Siscovick DS, et al. Association between language and risk factor levels among Hispanic adults with hypertension, hypercholesterolemia, or diabetes. Am Heart J. 2009 Jan;157(1):53–9. doi: 10.1016/j.ahj.2008.08.015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Moayad N, Balcazar H, Pedregon V, Velasco L, Bayona M. Do acculturation and family cohesiveness influence severity of diabetes among Mexican Americans? Ethn Dis. 2006 Spring;16(2):452–9. [PubMed] [Google Scholar]
- 13.Miranda JJ, Gilman RH, Garcia HH, Smeeth L. The effect on cardiovascular risk factors of migration from rural to urban areas in Peru: PERU MIGRANT Study. BMC Cardiovasc Disord. 2009;9:23. doi: 10.1186/1471-2261-9-23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.WHO . Reducing risks, promoting healthy life. Geneva, Switzerland: 2002. Contract No.: Document Number|. [Google Scholar]
- 15.Herrera VM, Casas JP, Miranda JJ, Perel P, Pichardo R, Gonzalez A, et al. Interethnic differences in the accuracy of anthropometric indicators of obesity in screening for high risk of coronary heart disease. Int J Obes (Lond) 2009 May;33(5):568–76. doi: 10.1038/ijo.2009.35. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Angel JL, Angel RJ. Age at migration, social connections, and well-being among elderly Hispanics. J Aging Health. 1992 Nov;4(4):480–99. doi: 10.1177/089826439200400402. [DOI] [PubMed] [Google Scholar]
- 17.Scribner R. Paradox as paradigm--the health outcomes of Mexican Americans. Am J Public Health. 1996 Mar;86(3):303–5. doi: 10.2105/ajph.86.3.303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Lizarzaburu JL, Palinkas LA. Immigration, acculturation, and risk factors for obesity and cardiovascular disease: a comparison between Latinos of Peruvian descent in Peru and in the United States. Ethn Dis. 2002 Summer;12(3):342–52. [PubMed] [Google Scholar]
- 19.Sundquist J, Winkleby M. Country of birth, acculturation status and abdominal obesity in a national sample of Mexican-American women and men. Int J Epidemiol. 2000 Jun;29(3):470–7. [PubMed] [Google Scholar]
- 20.Pedersen D, Tremblay J, Errazuriz C, Gamarra J. The sequelae of political violence: assessing trauma, suffering and dislocation in the Peruvian highlands. Soc Sci Med. 2008 Jul;67(2):205–17. doi: 10.1016/j.socscimed.2008.03.040. [DOI] [PubMed] [Google Scholar]
- 21.Cantero PJ, Richardson JL, Baezconde-Garbanati L, Marks G. The association between acculturation and health practices among middle-aged and elderly Latinas. Ethn Dis. 1999 Spring-Summer;9(2):166–80. [PubMed] [Google Scholar]
- 22.Vaeth PA, Willett DL. Level of acculturation and hypertension among Dallas County Hispanics: findings from the Dallas Heart Study. Ann Epidemiol. 2005 May;15(5):373–80. doi: 10.1016/j.annepidem.2004.11.003. [DOI] [PubMed] [Google Scholar]
- 23.Lara M, Gamboa C, Kahramanian MI, Morales LS, Bautista DE. Acculturation and Latino health in the United States: a review of the literature and its sociopolitical context. Annu Rev Public Health. 2005;26:367–97. doi: 10.1146/annurev.publhealth.26.021304.144615. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Gee GC, Walsemann KM, Takeuchi DT. English proficiency and language preference: testing the equivalence of two measures. Am J Public Health. 2010 Mar;100(3):563–9. doi: 10.2105/AJPH.2008.156976. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Pischon T. Commentary: Use of the body mass index to assess the risk of health outcomes: time to say goodbye? Int J Epidemiol. Jan 19; doi: 10.1093/ije/dyp388. [DOI] [PubMed] [Google Scholar]