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Is there a healthy migrant effect in relation to oral health among adults in England?
Public Health 181 (2020) 53e58
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Original Research
Is there a healthy migrant effect in relation to oral health among adults in England? ~ iga Abad a, S. Scambler a, E. Bernabe a E.K. Delgado-Angulo a, b, *, F. Zún a b
Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London, UK Facultad de Estomatología, Universidad Peruana Cayetano Heredia, Lima, Peru
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 July 2019 Received in revised form 4 November 2019 Accepted 23 November 2019
Objective: The aim of the study was to assess the healthy migrant effect in relation to oral health among adults in England. Study design: This is a secondary data analysis of a nationally representative survey. Methods: Data from 13,373 adults of Irish, black Caribbean, Indian, Pakistani, Bangladeshi and Chinese ethnicity, who participated in the Health Survey for England, were analysed. The proportions of edentate and dentate adults with toothache in the last 6 months in first- and second-generation migrants within each ethnic group were compared with those in the white British (reference group) ethnic group in logistic regression models after adjusting for demographic factors and socio-economic position. Among first-generation migrants, the associations of age at arrival and length of residence with each oral health outcome were assessed in logistic regression models after adjusting for sociodemographic factors. Results: Compared with white British migrants, first-generation black Caribbean (odds ratio [OR]: 1.42) and second-generation Pakistani (OR: 3.16) migrants had higher odds of being edentulous, whereas firstgeneration Indian (OR: 0.62), Pakistani (OR: 0.62), Bangladeshi (OR: 0.41) and Chinese (OR: 0.49) migrants had lower odds. Among dentate adults, second-generation Irish (OR: 1.51) migrants, first- and second-generation black Caribbean (OR: 1.61 and 1.54, respectively) migrants, first-generation Indian (OR: 1.24) migrants and second-generation Pakistani (OR: 1.34) migrants had higher odds of having toothache in the past 6 months, whereas second-generation Bangladeshi (OR: 0.51) migrants had lower odds than white British. Age at arrival and length of residence were positively associated with being edentulous among first-generation black Caribbean, Pakistani and Bangladeshi migrants. Conclusion: Evidence on the healthy migrant effect was mixed, with more consistent findings seen for edentulousness among Asian groups. Black Caribbean migrants were generally the ethnic group with the worst oral health when compared with white British migrants. © 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Keywords: Ethnic groups Acculturation Socio-economic factors Oral health Tooth loss Toothache
Introduction There is a large body of research which suggests that new migrants moving into developed countries have better health status than those born there, a phenomenon termed the healthy migrant effect.1 The healthy migrant effect has been studied in the United States (US), particularly in relation to the Hispanic paradox,2,3 Canada4 and Europe,5,6 and this research seems to suggest that migrants experience lower mortality rates and better health (across some outcomes) than their native-born peers. This is often
* Corresponding author. Bessemer Road, London SE5 9RW, UK. E-mail address: [email protected] (E.K. Delgado-Angulo).
considered a paradox because migrants tend to have low social and economic status in their new countries and face a range of barriers including language and cultural differences.7 A common explanation for the healthy migrant effect is the selective nature of migration to Western countries.7 Those selfselecting into a subpopulation choosing to migrate are likely to be both healthy and in receipt of high levels of health and human capital.1,7 This means that, even when migrating from developing countries with higher mortality and morbidity rates than their destination countries, migrants are likely to bring a health advantage with them which will take time to dissipate.1,4 In addition, it has been suggested that the selection criteria in the destination country may advantage those with good health and make it more likely that they will choose to, or be able to, migrate, and that those
https://doi.org/10.1016/j.puhe.2019.11.025 0033-3506/© 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
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with poorer health are less likely to succeed as migrants and are thus more likely to return to the country of origin and disappear from the statistics.6,7 The picture is however more nuanced than a simple health advantage enjoyed by migrants, and there is evidence of variations across the life course and as per the outcome studied, with children, adolescents and older people experiencing less positive effects than those in adulthood.3,4,8 Others have also argued that the impact of the healthy migrant effect needs to be studied over time and that both before leaving the home country and once in the destination country, the experiences of migrants will be very different from either native-born or second-generation minority populations.9e11 This incorporates both the economic and social upheavals of the move itself and also the specific challenges of becoming established in a new country, learning a language, establishing a social network, finding work and shelter and so forth.9,11 It is perhaps unsurprising that these experiences have a long-term detrimental effect on the health of migrants, even when they entered the country healthy.1 Recent reviews suggest that the healthy migrant effect is strongest within the first 10 years of migration and vanishes over time.3,4,8 Putting this into the context of an ageing ethnic minority population in the UK, Nazroo and Williams12 suggest that both hazards encountered in early life (premigration) and risks accumulated through the life course (often related to low socioeconomic status and experiences of discrimination) detrimentally affect the health of those who may have migrated as healthy children or young adults, thus diminishing any healthy migrant effect over the life course. There is some evidence that the healthy migrant effect is applicable to oral health. Longitudinal studies in Canada13 and Israel14 showed that the dental status of new migrants worsened rapidly after arrival (i.e., in 4e5 years) but without reaching the poorer levels of the host populations. National US data also support such an effect. Sanders15 found that foreign- but not native-born Latinos had better oral healtherelated quality of life than the host population, although the same pattern was not found among other migrants. In addition, altough non-citizen migrants were also more likely to have periodontal disease and report poorer oral health than natives, naturalised migrants were not different from natives.16 A recent study in East London, England, found differences in caries experience between foreign- and native-born migrants with variations by ethnicity. White migrants had worse dental status, whereas all black and Asians groups had better dental status than their counterparts of the same ethnic group.17 It is within this context that this article sought to assess whether the healthy migrant effect could be seen in national data on oral health among ethnic minority groups in England. Methods Data source The Health Survey for England (HSE) is an annual survey that selects a nationally representative sample of private households, using stratified two-stage probability sampling.18 An oversample of ethnic minority groups was surveyed in 1999, which included residents in England who self-described their origin as being Bangladeshi, black Caribbean, Chinese, Indian, Irish or Pakistani. They were the largest seven non-mixed ethnic minority groups living in England as per the 2001 UK census. Participants who described themselves as white British formed the reference group. A total of 13,974 adults, aged 16 years and older, participated in the survey. Of them, we excluded 311 participants because they did not belong to the selected ethnic groups (165 white Europeans and 43 black Africans) or were white British born abroad (n ¼ 103). Of
the 13,663 eligible participants, we further excluded 290 participants because of missing values in one or more of the following variables: ethnicity (n ¼ 218), country of birth (n ¼ 53), year they first moved to the UK (n ¼ 49) and oral health (n ¼ 13). Therefore, the study sample included 13,373 adults with complete data on all relevant variables (97.9% of the 13,663 eligible participants). Variable selection Information on two oral health outcomes, edentulousness and toothache, was collected as part of the interviews in participants' homes. The participants were first asked whether they still have some of their own teeth or have lost them all, and the participants with some remaining teeth were subsequently asked whether they had experienced any toothache in the last 6 months. The prevalence of adults with edentulousness and that of those with toothache were the two outcome measures used for this study. Ethnicity was self-reported as per the participant's family origins, with respondents classified as white British, Irish, black Caribbean, Indian, Pakistani, Bangladeshi and Chinese. Generational status was determined based on the responses given to the questions regarding ethnicity and country of birth. First-generation migrants were nonewhite British participants born abroad, and second-generation migrants were nonewhite British participants born in Great Britain. First-generation migrants were also asked the year they first moved to the UK. This information along with the participants' age at the time of the survey and the survey year was used to estimate two additional indicators of migration history, namely, length of residence and age at arrival. Length of residence in the host country was calculated by subtracting the year they first moved to the UK from the survey year. Age at arrival was calculated by subtracting length of residence from the participants' age. Four measures of socio-economic position (SEP) were chosen to address concerns about their applicability across different ethnic groups. They were education (indicated by the highest formal educational qualification), social class (based on the occupation of the household's head), annual equivalised household income and current economic activity. A composite SEP measure was derived from fitting a one-factor model in confirmatory factor analysis.19 Education, social class, economic activity and income were assigned to a single latent construct representing SEP. Full information maximum likelihood estimation was used to handle nonresponse in SEP measures. As some SEP measures were collected using categorical scales, the weighted least square method was used to estimate model parameters. Factor loadings were all significant and ranged from 0.60 to 0.76. The comparative fit index was 0.99, and the root mean square error of approximation was 0.039, suggesting the model was a good fit to the data. The SEP latent factor score was categorised into quintiles (Q1 ¼ wealthiest, Q5 ¼ poorest).19 Other variables included in the analysis were demographic characteristics (sex and age). Data analyses All analyses were conducted using Stata 15 (StataCorp LP, College Station, TX, USA). Weights were used to account for unequal probability of selection and non-response rates. First- and secondgeneration migrants within each ethnic group were compared against white British (reference group) in terms of demographic factors and the composite measure of SEP using the chi-squared test. The association between generational status and each oral health outcome was assessed in logistic regression models. Odds ratios (ORs) were therefore reported. As there were few cases of edentulousness within some groups (after cross-tabulating
E.K. Delgado-Angulo et al. / Public Health 181 (2020) 53e58
55
first-generation Indian migrants occupied a lower SEP than white British migrants. First- and second-generation Bangladeshi migrants were the most socially disadvantaged group, followed by first-generation black Caribbean and Pakistani migrants. There were large inequalities in edentulousness by generational status. Edentulousness was more common among first-generation black Caribbean and Irish migrants than among white British migrants, whereas edentulousness was less common in all other groups (Table 2). After adjustments for demographic factors and SEP, first-generation black Caribbean (OR: 1.42, 95% CI: 1.11e1.82) and second-generation Pakistani (OR: 3.16, 95% CI: 1.46e6.87) migrants had higher odds of being edentulous whereas firstgeneration Indian (OR: 0.62, 95% CI: 0.45e0.86), Pakistani (OR: 0.62, 95% CI: 0.42e0.93), Bangladeshi (OR: 0.41, 95% CI: 0.28e0.58) and Chinese (OR: 0.49, 95% CI: 0.31e0.77) migrants had lower odds of being edentulous than white British migrants. A different pattern was found for toothache among dentate adults, which was more common in black Caribbean (both generations), Pakistani (both generations), first-generation Bangladeshi, second-generation Irish and first-generation Indian migrants than in white British migrants (Table 3). Toothache was less common among second-generation Bangladeshi migrants. Some of these differences became nonsignificant after adjustment for demographic factors and SEP. In the adjusted model, second-generation Irish (OR: 1.51, 95% CI: 1.25e1.84), first- (OR: 1.61, 95% CI: 1.30e1.99) and secondgeneration black Caribbean (OR: 1.54, 95% CI: 1.20e1.87), firstgeneration Indian (OR: 1.24, 95% CI: 1.03e1.49), and secondgeneration Pakistani (OR: 1.34, 95% CI: 1.04e1.74) migrants had higher odds of having toothache whereas second-generation Bangladeshi migrants had lower odds (OR: 0.51, 95% CI: 0.30e0.86) of having toothache than white British migrants. The interaction between age and generational status was not significant when added to model 1B or 2B. Among first-generation migrants, the mean age at arrival was 20.6 years (SD: 11.4, range: 0e79), and the mean length of residence in the host country was 24.1 years (SD: 13.4, range: 0e79), with large variation between ethnic groups. Irish and black Caribbean migrants were significantly younger at arrival and had lived in the country longer than all Asian groups (Table 4). Both indicators were positively associated with higher odds of being edentulous among all ethnic groups. After adjustments for demographic factors, SEP and the other indicator of migration status, associations remained significant only for black Caribbean, Indian and Pakistani migrants. In these groups, the odds of being edentulous increased
ethnicity with generational status), we used a penalised maximum likelihood estimation to overcome potential issues of complete separation (i.e., a situation where maximum likelihood estimates tend to infinity and thus become inestimable).20 The modelling strategy was first to estimate the crude association of generational status with edentulousness (Model 1A), and then adjust for sex, continuous age and the composite measure of SEP (Model 1B). A two-way statistical interaction (product term) between continuous age and generational status was added to model 1B to test whether the healthy migrant effect varied based on age. A similar set of models was fitted with toothache (models 2A and 2B), although the sample was restricted to dentate adults (n ¼ 12,130). Alternative parameterisations for age were tested in sensitivity analysis (i.e., treating age as a categorical variable or using non-linear forms). Among first-generation migrants, the association of age at arrival and length of residence with each outcome was explored in crude and adjusted models (models 3A and 3B for edentulousness and models 4A and 4B for toothache), stratified by ethnic groups. As age, age at arrival and length of residence are mathematically correlated (length of residence ¼ age e age at arrival), we dealt with collinearity by treating age as a categorical variable (10-year brackets) and the other indicators as a continuous variable. In sensitivity analysis, we included two indicators at a time (continuous age and one of the other indicators). Results Data from 13,373 adults (54% women) were analysed. The participants' mean age was 43.8 years (standard deviation [SD]: 18.0, range: 16e96). Overall, 9.2% (95% confidence interval [CI]: 8.7e9.7) reported being edentulous, and 24.0% (95% CI: 23.2e24.8) of the 12,130 dentate adults reported experiencing toothache in the past 6 months. Participants excluded because of missing data were more likely to be white British than those in the study sample. The sociodemographic composition of the sample by ethnicity and generational status is presented in Table 1. Compared with women among white British migrants, there was a significantly high proportion of women among second-generation black Caribbean migrants and a low proportion among first-generation Pakistani and second-generation Chinese migrants. All second-generation ethnic groups were significantly younger than white British migrants. Among first-generation migrants, Irish and black Caribbean migrants were older, whereas all Asian groups were younger than white British migrants. All groups but second-generation Irish and
Table 1 Sociodemographic characteristics of the sample by ethnicity and generational status. Sociodemographic characteristics
Sample (na) Sex, % Men Women Age (in years) Mean (SD) SEP, % Q1 (wealthiest) Q2 Q3 Q4 Q5 (poorest)
White British
6520
Irish
Black Caribbean
Indian
2nd
1st
2nd
1st
2nd
1st
Pakistani 2nd
1st
Bangladeshi 2nd
1st
Chinese 2nd
1st
774
496
654
634
341
927
408
849
137
954
121
558
45.8 54.2
43.4 56.6
43.8 56.2
40.3 59.7
44.1 56.0
49.9 50.1
48.4 51.6
44.8 55.2
51.4 48.6
47.4 52.6
49.2 50.8
55.0 45.0
43.3 56.7
48.0 (18.5)
42.4 (15.3)
52.1 (18.6)
29.9 (8.3)
55.1 (14.3)
24.9 (7.5)
46.3 (13.9)
23.4 (6.1)
40.1 (13.6)
21.2 (5.1)
36.9 (15.5)
25.3 (11.1)
44.4 (13.4)
24.6 23.8 20.0 17.5 14.1
27.6 24.4 22.0 14.1 11.9
22.3 18.6 20.4 19.6 19.1
16.9 23.6 21.2 17.9 20.4
7.9 15.6 17.3 24.3 34.9
21.8 19.0 26.1 21.4 11.7
21.7 16.4 24.8 20.9 16.2
11.6 12.8 22.1 31.0 22.5
8.9 12.7 19.3 30.8 28.5
2.6 13.1 14.6 28.8 41.0
2.3 4.8 9.7 24.2 58.9
16.2 25.9 26.3 21.8 9.9
23.6 18.7 22.6 19.3 15.9
SEP: socio-economic position; SD: standard deviation. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). a Counts are unweighted.
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E.K. Delgado-Angulo et al. / Public Health 181 (2020) 53e58
Table 2 Models for the association between generational status and edentulousness (n ¼ 13,373 adults). Generational status per ethnic group
White British Irish 2nd Irish 1st Black Caribbean 2nd Black Caribbean 1st Indian 2nd Indian 1st Pakistani 2nd Pakistani 1st Bangladeshi 2nd Bangladeshi 1st Chinese 2nd Chinese 1st
Sample sizea
6520 774 496 654 634 341 927 408 849 137 954 121 558
Edentulousness
Model 1Ab
Model 1Bb
na
%
(95% CI)
ORc (95% CI)
ORc (95% CI)
793 48 100 6 141 3 51 6 33 0 37 1 21
12.2 6.7 17.7 0.7 21.9 0.9 6.1 1.6 4.0 0.0 3.5 1.3 3.6
(11.4e13.0) (4.9e9.1) (14.2e21.9) (0.3e1.7) (18.7e25.4) (0.2e3.9) (4.6e8.1) (0.7e3.9) (2.8e5.7) (0-0) (2.4e5.1) (0.2e8.8) (2.3e5.6)
1.00 0.52 1.54 0.07 2.12 0.07 0.41 0.14 0.30 0.02 0.28 0.13 0.30
1.00 0.98 1.28 0.72 1.42 1.34 0.62 3.16 0.62 0.47 0.41 1.12 0.49
(Reference) (0.40e0.69)*** (1.20e1.98)** (0.03e0.15)*** (1.73e2.60)*** (0.03e0.21)*** (0.31e0.55)*** (0.07e0.28)*** (0.21e0.43)*** (0.00e0.32)** (0.20e0.38)*** (0.04e0.45)** (0.20e0.45)***
(Reference) (0.70e1.39) (0.93e1.75) (0.29e1.78) (1.11e1.82)** (0.42e4.28) (0.45e0.86)** (1.46e6.87)** (0.42e0.93)* (0.03e7.63) (0.28e0.58)*** (0.22e5.80) (0.31e0.77)**
CI: confidence interval; OR: odds ratio. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). *P < 0.05; **P < 0.01; ***P < 0.001. a Counts are unweighted for sample size (N) and people with the outcome (n). b Model 1A was unadjusted. Model 1B was adjusted for sex, continuous age and the composite measure of socio-economic position. c Penalised logistic regression was fitted, and ORs were reported.
Table 3 Models for the association between generational status and toothache in the past 6 months (n ¼ 12130 dentate adults). Generational status per ethnic group
Sample sizea
n White British Irish 2nd Irish 1st Black Caribbean 2nd Black Caribbean 1st Indian 2nd Indian 1st Pakistani 2nd Pakistani 1st Bangladeshi 2nd Bangladeshi 1st Chinese 2nd Chinese 1st
5726 726 395 648 493 338 876 402 816 137 917 120 536
Model 2Ab
Toothache a
1229 212 88 205 154 85 216 108 202 23 225 21 119
c
Model 2Bb
%
(95% CI)
OR (95% CI)
ORc (95% CI)
21.5 29.4 24.8 31.0 31.2 26.4 25.4 28.3 25.3 13.4 25.3 15.4 21.5
(20.4e22.6) (25.8e33.4) (20.0e30.3) (27.4e34.9) (27.0e35.6) (21.4e32.0) (22.2e28.7) (23.8e33.3) (22.3e28.6) (8.5e20.5) (21.9e29.1) (10.0e23.0) (18.1e25.4)
1.00 1.53 1.21 1.65 1.66 1.31 1.24 1.44 1.24 0.57 1.24 0.67 1.00
1.00 1.51 1.21 1.54 1.61 1.25 1.24 1.34 1.19 0.51 1.13 0.64 0.99
(Reference) (1.26e1.85)*** (0.91e1.60) (1.37e1.98)*** (1.34e2.04)*** (0.99e1.73) (1.03e1.49)* (1.13e1.84)** (1.04e1.48)* (0.34e0.94)* (1.01e1.51)* (0.41e1.10) (0.80e1.26)
(Reference) (1.25e1.84)*** (0.91e1.60) (1.20e1.87)*** (1.30e1.99)*** (0.94e1.68) (1.03e1.49)* (1.04e1.74)* (0.99e1.43) (0.30e0.86)* (0.91e1.40) (0.39e1.06) (0.79e1.24)
CI: confidence interval; OR: odds ratio. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). *P < 0.05; **P < 0.01; ***P < 0.001. a Counts are unweighted for sample size and people with the outcome (n). b Model 2A was unadjusted. Model 2B was adjusted for sex, continuous age and the composite measure of socio-economic position. c Logistic regression was fitted, and ORs were reported.
by around 1.10e1.21 times per year increase in age at arrival and by around 1.11e1.27 times per year increase in length of residence. Contrarily, neither age at arrival nor length of residence was significantly associated with toothache among first-generation dentate migrants. Similar findings were obtained in sensitivity analysis (using continuous age and either of the two indicators).
Discussion This study provides mixed support to the healthy migrant effect on oral health among adults in England, with marked variations based on the ethnic groups and oral health outcomes. The odds of being edentulous converged to those of the host population among all Asian groups, with evidence of an ‘overshoot’ (second-generation migrants worse than white British migrants) among Pakistani migrants. The healthy migrant effect was not evident for toothache. All migrant groups but second-generation Bangladeshi migrants had either higher or similar odds of reporting toothache than white British migrants.
The large variation seen across ethnic groups implies that the findings cannot be entirely attributed to self-selection into migration. Alternative explanations include the social determinants of health and acculturation, which might interact with each other to affect migrants' oral health.10,21 Although we controlled for current SEP, social circumstances in the sending country are also important as they will affect migrants' health throughout the life course (before, during and after relocation).9,10 Once in the new country, migrants may be subject to racism and discrimination,22,23 with the emerging literature linking both to oral health.24 Policies to improve access to health care might also be important for migrants' oral health, with evidence from the US suggesting that having health insurance could mitigate inequalities between non-citizens and natives.16 In this regard, edentulousness could be considered a sequel of having access to Western dentistry for longer time span (among first-generation migrants) or for a lifetime (among white British and second-generation migrants). As for cultural explanations, migrants may arrive with more favourable behaviours than those practised by the host population. Oral conditions have a strong behavioural component. Aside from
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Table 4 Models for the association of age at arrival and length of residence with oral health outcomes among first-generation migrants by ethnicity. Ethnicity
Edentulousness Meand
(95% CI)
Model 3Aa b
Toothache
Model 3Ba
Meand
(95% CI)
b
Model 4Aa b
Model 4Ba
OR (95% CI)
ORb (95% CI)
(13.9e16.1) (27.7e30.0)
0.98 (0.97e1.00) 0.98 (0.95e1.01)
0.92 (0.84e1.02) 0.92 (0.83e1.02)
15.7 28.2
(14.9e16.4) (27.4e29.0)
1.00 (0.98e1.02) 1.00 (0.98e1.02)
1.01 (0.93e1.09) 1.01 (0.93e1.09)
1.10 (0.97e1.25) 1.12 (0.99e1.27)
20.5 23.3
(19.8e21.2) (22.6e24.0)
1.02 (1.00e1.03) 1.00 (0.98e1.02)
0.98 (0.92e1.05) 0.98 (0.92e1.04)
1.09 (1.05e1.13)*** 1.08 (1.05e1.11)***
1.21 (1.04e1.40)* 1.21 (1.05e1.40)**
21.0 22.9
(20.3e21.7) (22.2e23.6)
1.02 (1.00e1.03) 1.01 (0.99e1.03)
0.98 (0.92e1.05) 0.97 (0.91e1.04)
(21.5e23.1) (20.7e22.3)
1.11 (1.08e1.14)*** 1.07 (1.04e1.09)***
1.17 (1.03e1.34)* 1.17 (1.03e1.34)*
22.3 21.6
(21.4e23.1) (20.8e22.4)
1.04 (1.02e1.06) 1.02 (1.00e1.04)
1.03 (0.96e1.11) 1.01 (0.94e1.08)
(21.9e23.3) (20.5e21.9)
1.07 (1.03e1.12)** 1.09 (1.06e1.12)***
0.97 (0.80e1.18) 0.99 (0.82e1.20)
22.5 21.4
(21.8e23.2) (20.7e22.1)
1.01 (0.99e1.03) 1.01 (0.99e1.03)
0.99 (0.91e1.08) 0.99 (0.91e1.08)
OR (95% CI)
OR (95% CI)
(12.6e14.7) (29.2e31.3)
1.10 (1.07e1.12)*** 1.05 (1.02e1.07)**
1.04 (0.94e1.14) 1.04 (0.93e1.15)
15.0 28.9
(15.1e16.5) (27.3e28.7)
1.14 (1.09e1.18)*** 1.12 (1.09e1.15)***
1.10 (1.00e1.21)* 1.11 (1.01e1.21)*
(20.3e21.7) (22.2e23.6)
1.06 (1.03e1.09)** 1.11 (1.09e1.14)***
(20.4e21.8) (22.1e23.4)
c
Irish (n ¼ 449 and 391) Age at arrival 13.6 Length of residence 30.2 Black Caribbean (nc ¼ 594 and 492) Age at arrival 15.8 Length of residence 28.0 Indian (nc ¼ 950 and 871) Age at arrival 21.0 Length of residence 22.9 c Pakistani (n ¼ 783 and 800) Age at arrival 21.1 Length of residence 22.7 Bangladeshi (nc ¼ 1158 and 905) Age at arrival 22.3 Length of residence 21.5 c Chinese (n ¼ 580 and 503) Age at arrival 22.6 Length of residence 21.2
CI: confidence interval; OR: odds ratio. *P < 0.05; **P < 0.01; ***P < 0.001. a Model A was unadjusted. Model B was adjusted for sex, age (categorical), the composite measure of socio-economic position and the other indicator of migration status. b Penalised logistic regression was fitted for edentulousness and logistic regression for toothache. ORs were reported in both cases. c Number of first-generation migrants for models of edentulousness and toothache, respectively. d Predicted means derived from linear models regressing age at arrival/length of residence on sex, continuous age and the composite measure of socio-economic position.
lower smoking rates,25 diets are generally healthier in sending countries (less availability of ready-to-eat meals and foods high in free sugars), which last until internalisation of the new culture and lifestyles occurs.26 In addition, the availability of social networks in the receiving country could provide emotional and instrumental support to migrants.3,11 There is evidence that members of minority ethnic groups are healthier when living in enclaves of their own ethnic group, the so-called ethnic density effect.27,28 The findings among the black Caribbean and Irish migrants in this study did not conform to the healthy migrant hypothesis. Black Caribbean migrants had worse oral health and Irish migrants were not different than the white British population. However, these patterns are not specific to oral health.12,29 Black Caribbean migrants often exhibit worse health than the white population in England, even among second-generation migrants despite relative improvements in social and economic circumstances compared with first-generation migrants.30 Contrary to migration from Commonwealth countries, which happened to address a need for labour after World War II, Irish people have a longer history of migration. Although the first cohorts of Irish migrants were typically in worse health than the host population, new Irish cohorts either born in or moving to England are healthier.29 A number of factors could help explain the different findings with edentulousness and toothache. Edentulousness is a cumulative condition resulting from history of dental diseases, access to dental care, and people's attitudes and behaviours as well as those of the dentist.31 On the contrary, toothache is a transient condition that can sometimes be managed without a visit to the dentist. This is in addition to physiological differences in experimentally induced pain between ethnic groups, with ethnic minority groups having high pain sensitivity, lower pain tolerance but similar pain thresholds than whites.32 Edentulousness is also almost exclusively a condition of older people. First-generation black Caribbean migrants in this study were older, whereas all Asian groups were younger than the white British population. We controlled for age in all regression models, and our findings were unchanged when using alternative age parameterisations. We did not find a
significant interaction between age and generational status either. Although residual confounding cannot be ruled out, we are confident that our findings reflect more than just model misspecification. Furthermore, data on toothache were collected among dentate adults only, which could have made ethnic groups more homogenous as those with the worst oral health (edentulous) had already been excluded. The use of nationally representative data and the large sample size for the main minority ethnic groups in England are strengths of this study. However, this study is not without limitations. First, using cross-sectional data limited our ability to establish temporal order between variables. This is relevant for edentulousness, which could have occurred before migration. Second, we used relatively old data. However, HSE 1999 remains the most recent health survey of ethnic minorities with oral health data in England. The HSE 2004 included the latest ethnic boost sample, but it did not include any oral health data. In addition, the latest Adult Dental Health Survey, carried out in 2009, did not collect data on migration status. That said, although it is unlikely that oral health inequalities by ethnicity and migration status had changed in such a short time, data from emerging minority ethnic groups in England, such as black Africans and Eastern Europeans, could not be included in the present analysis. Third, some may question the validity of self-reports on edentulousness. However, self-reports were found valid when compared against clinically determined tooth loss.33,34 Indeed, the proportion of edentulous adults in this study was similar to that reported for England in the 2009 Adult Dental Health Survey. Further research would benefit from using broader frameworks emphasising the social determinants of health in both sending and receiving countries.7,9,11 Upon arrival, a better understanding is needed on how the new social context modifies the assimilation of migrants to the new culture and its subsequent impact on oral health.21 Qualitative life history research exploring the experiences of first- and second-generation migrants in relation to oral health, dental behaviours and diet would also enable us to better explain the nuances of the data. These strategies could help unravel some of the push and pull factors behind families' decision to relocate.
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Conclusion This study found mixed evidence for the healthy migrant effect on adult oral health in England. The healthy migrant effect was more consistently observed for edentulousness and among Asian groups. Black Caribbean people had the worst oral health when compared with the white British population. Author statements Ethical approval This is a secondary analysis of a national survey with ethical approval; no ethical approval was sought for this study. Funding No funding has been received for this research. Competing interests The authors have no competing interests. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.puhe.2019.11.025. References 1. Roura M. Unravelling migrants' health paradoxes: a transdisciplinary research agenda. J Epidemiol Community Health 2017;71:870e3. 2. 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;26:367e97. 3. Shor E, Roelfs D, Vang ZM. The "Hispanic mortality paradox" revisited: metaanalysis and meta-regression of life-course differentials in Latin American and Caribbean immigrants' mortality. Soc Sci Med 2017;186:20e33. 4. Vang ZM, Sigouin J, Flenon A, Gagnon A. Are immigrants healthier than nativeborn Canadians? A systematic review of the healthy immigrant effect in Canada. Ethn Health 2017;22:209e41. 5. Moullan Y, Jusot F. Why is the 'healthy immigrant effect' different between European countries? Eur J Public Health 2014;24:80e6. 6. Constant AF, Garcia-Munoz T, Neuman S, Neuman T. A "healthy immigrant effect" or a "sick immigrant effect"? Selection and policies matter. Eur J Health Econ 2018;19:103e21. 7. Jasso G, Massey DS, Rosenzweig MR, Smith JP. Immigrant health: selectivity and acculturation. In: Anderson NB, Bulatao RA, Cohen B, editors. Critical perspectives on racial and ethnic differences in health in late life. Washington DC: National Academy Press; 2004. p. 227e66. 8. Markides KS, Rote S. The healthy immigrant effect and aging in the United States and other western countries. Gerontol 2019;59:205e14. 9. Spallek J, Zeeb H, Razum O. What do we have to know from migrants' past exposures to understand their health status? a life course approach. Emerg Themes Epidemiol 2011;8:6.
10. Acevedo-Garcia D, Sanchez-Vaznaugh EV, Viruell-Fuentes EA, Almeida J. Integrating social epidemiology into immigrant health research: a cross-national framework. Soc Sci Med 2012;75:2060e8. 11. Viruell-Fuentes EA, Miranda PY, Abdulrahim S. More than culture: structural racism, intersectionality theory, and immigrant health. Soc Sci Med 2012;75: 2099e106. 12. Nazroo JY, Williams DR. The social determination of ethnic/racial inequalities in health. In: Marmot M, Wilkinson RG, editors. Social determinants of health. 2nd ed. Oxford: Oxford University Press; 2006. p. 238e66. 13. Calvasina P, Muntaner C, Quinonez C. The deterioration of Canadian immigrants' oral health: analysis of the Longitudinal Survey of Immigrants to Canada. Community Dent Oral Epidemiol 2015;43:424e32. 14. Vered Y, Soskolne V, Zini A, Livny A, Sgan-Cohen HD. Psychological distress and social support are determinants of changing oral health status among an immigrant population from Ethiopia. Community Dent Oral Epidemiol 2011;39: 145e53. 15. Sanders AE. A Latino advantage in oral health-related quality of life is modified by nativity status. Soc Sci Med 2010;71:205e11. 16. Wilson FA, Wang Y, Borrell LN, Bae S, Stimpson JP. Disparities in oral health by immigration status in the United States. J Am Dent Assoc 2018;149:414e21. e3. 17. Delgado-Angulo EK, Marcenes W, Harding S, Bernabe E. Ethnicity, migration status and dental caries experience among adults in East London. Community Dent Oral Epidemiol 2018;46:392e9. 18. Mindell J, Biddulph JP, Hirani V, Stamatakis E, Craig R, Nunn S, et al. Cohort profile: the health survey for England. Int J Epidemiol 2012;41:1585e93. 19. Delgado-Angulo EK, Mangal M, Bernabe E. Socioeconomic inequalities in adult oral health across different ethnic groups in England. Health Qual Life Outcomes 2019;17:85. 20. Heinze G, Schemper M. A solution to the problem of separation in logistic regression. Stat Med 2002;21:2409e19. 21. Fox M, Thayer Z, Wadhwa PD. Acculturation and health: the moderating role of socio-cultural context. Am Anthropol 2017;119:405e21. 22. Phelan JC, Link BG. Is racism a fundamental cause of inequalities in health? Annu Rev Sociol 2015;41:311e30. 23. Williams DR, Lawrence JA, Davis BA. Racism and health: evidence and needed research. Annu Rev Public Health 2019;40:105e25. 24. Bastos JL, Celeste RK, Paradies YC. Racial inequalities in oral health. J Dent Res 2018;97:878e86. 25. Gazard B, Frissa S, Nellums L, Hotopf M, Hatch SL. Challenges in researching migration status, health and health service use: an intersectional analysis of a South London community. Ethn Health 2015;20:564e93. 26. Leung G, Stanner S. Diets of minority ethnic groups in the UK: influence on chronic disease risk and implications for prevention. Nutr Bull 2011;36: 161e98. 27. Pickett KE, Wilkinson RG. People like us: ethnic group density effects on health. Ethn Health 2008;13:321e34. 28. Becares L, Shaw R, Nazroo J, Stafford M, Albor C, Atkin K, et al. Ethnic density effects on physical morbidity, mortality, and health behaviors: a systematic review of the literature. Am J Public Health 2012;102. e33-66. 29. Delaney L, Fernihough A, Smith JP. Exporting poor health: the Irish in England. Demography 2013;50:2013e35. 30. Nazroo J, Jackson J, Karlsen S, Torres M. The Black diaspora and health inequalities in the US and England: does where you go and how you get there make a difference? Sociol Health Illn 2007;29:811e30. 31. Kassebaum NJ, Bernabe E, Dahiya M, Bhandari B, Murray CJ, Marcenes W. Global burden of severe tooth loss: a systematic review and meta-analysis. J Dent Res 2014;93. 20S-8S. 32. Kim HJ, Yang GS, Greenspan JD, Downton KD, Griffith KA, Renn CL, et al. Racial and ethnic differences in experimental pain sensitivity: systematic review and meta-analysis. Pain 2017;158:194e211. 33. Pitiphat W, Garcia RI, Douglass CW, Joshipura KJ. Validation of self-reported oral health measures. J Public Health Dent 2002;62:122e8. 34. Gilbert GH, Chavers LS, Shelton BJ. Comparison of two methods of estimating 48-month tooth loss incidence. J Public Health Dent 2002;62:163e9.
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Original Research
Is there a healthy migrant effect in relation to oral health among adults in England? ~ iga Abad a, S. Scambler a, E. Bernabe a E.K. Delgado-Angulo a, b, *, F. Zún a b
Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London, UK Facultad de Estomatología, Universidad Peruana Cayetano Heredia, Lima, Peru
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 July 2019 Received in revised form 4 November 2019 Accepted 23 November 2019
Objective: The aim of the study was to assess the healthy migrant effect in relation to oral health among adults in England. Study design: This is a secondary data analysis of a nationally representative survey. Methods: Data from 13,373 adults of Irish, black Caribbean, Indian, Pakistani, Bangladeshi and Chinese ethnicity, who participated in the Health Survey for England, were analysed. The proportions of edentate and dentate adults with toothache in the last 6 months in first- and second-generation migrants within each ethnic group were compared with those in the white British (reference group) ethnic group in logistic regression models after adjusting for demographic factors and socio-economic position. Among first-generation migrants, the associations of age at arrival and length of residence with each oral health outcome were assessed in logistic regression models after adjusting for sociodemographic factors. Results: Compared with white British migrants, first-generation black Caribbean (odds ratio [OR]: 1.42) and second-generation Pakistani (OR: 3.16) migrants had higher odds of being edentulous, whereas firstgeneration Indian (OR: 0.62), Pakistani (OR: 0.62), Bangladeshi (OR: 0.41) and Chinese (OR: 0.49) migrants had lower odds. Among dentate adults, second-generation Irish (OR: 1.51) migrants, first- and second-generation black Caribbean (OR: 1.61 and 1.54, respectively) migrants, first-generation Indian (OR: 1.24) migrants and second-generation Pakistani (OR: 1.34) migrants had higher odds of having toothache in the past 6 months, whereas second-generation Bangladeshi (OR: 0.51) migrants had lower odds than white British. Age at arrival and length of residence were positively associated with being edentulous among first-generation black Caribbean, Pakistani and Bangladeshi migrants. Conclusion: Evidence on the healthy migrant effect was mixed, with more consistent findings seen for edentulousness among Asian groups. Black Caribbean migrants were generally the ethnic group with the worst oral health when compared with white British migrants. © 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Keywords: Ethnic groups Acculturation Socio-economic factors Oral health Tooth loss Toothache
Introduction There is a large body of research which suggests that new migrants moving into developed countries have better health status than those born there, a phenomenon termed the healthy migrant effect.1 The healthy migrant effect has been studied in the United States (US), particularly in relation to the Hispanic paradox,2,3 Canada4 and Europe,5,6 and this research seems to suggest that migrants experience lower mortality rates and better health (across some outcomes) than their native-born peers. This is often
* Corresponding author. Bessemer Road, London SE5 9RW, UK. E-mail address: [email protected] (E.K. Delgado-Angulo).
considered a paradox because migrants tend to have low social and economic status in their new countries and face a range of barriers including language and cultural differences.7 A common explanation for the healthy migrant effect is the selective nature of migration to Western countries.7 Those selfselecting into a subpopulation choosing to migrate are likely to be both healthy and in receipt of high levels of health and human capital.1,7 This means that, even when migrating from developing countries with higher mortality and morbidity rates than their destination countries, migrants are likely to bring a health advantage with them which will take time to dissipate.1,4 In addition, it has been suggested that the selection criteria in the destination country may advantage those with good health and make it more likely that they will choose to, or be able to, migrate, and that those
https://doi.org/10.1016/j.puhe.2019.11.025 0033-3506/© 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
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with poorer health are less likely to succeed as migrants and are thus more likely to return to the country of origin and disappear from the statistics.6,7 The picture is however more nuanced than a simple health advantage enjoyed by migrants, and there is evidence of variations across the life course and as per the outcome studied, with children, adolescents and older people experiencing less positive effects than those in adulthood.3,4,8 Others have also argued that the impact of the healthy migrant effect needs to be studied over time and that both before leaving the home country and once in the destination country, the experiences of migrants will be very different from either native-born or second-generation minority populations.9e11 This incorporates both the economic and social upheavals of the move itself and also the specific challenges of becoming established in a new country, learning a language, establishing a social network, finding work and shelter and so forth.9,11 It is perhaps unsurprising that these experiences have a long-term detrimental effect on the health of migrants, even when they entered the country healthy.1 Recent reviews suggest that the healthy migrant effect is strongest within the first 10 years of migration and vanishes over time.3,4,8 Putting this into the context of an ageing ethnic minority population in the UK, Nazroo and Williams12 suggest that both hazards encountered in early life (premigration) and risks accumulated through the life course (often related to low socioeconomic status and experiences of discrimination) detrimentally affect the health of those who may have migrated as healthy children or young adults, thus diminishing any healthy migrant effect over the life course. There is some evidence that the healthy migrant effect is applicable to oral health. Longitudinal studies in Canada13 and Israel14 showed that the dental status of new migrants worsened rapidly after arrival (i.e., in 4e5 years) but without reaching the poorer levels of the host populations. National US data also support such an effect. Sanders15 found that foreign- but not native-born Latinos had better oral healtherelated quality of life than the host population, although the same pattern was not found among other migrants. In addition, altough non-citizen migrants were also more likely to have periodontal disease and report poorer oral health than natives, naturalised migrants were not different from natives.16 A recent study in East London, England, found differences in caries experience between foreign- and native-born migrants with variations by ethnicity. White migrants had worse dental status, whereas all black and Asians groups had better dental status than their counterparts of the same ethnic group.17 It is within this context that this article sought to assess whether the healthy migrant effect could be seen in national data on oral health among ethnic minority groups in England. Methods Data source The Health Survey for England (HSE) is an annual survey that selects a nationally representative sample of private households, using stratified two-stage probability sampling.18 An oversample of ethnic minority groups was surveyed in 1999, which included residents in England who self-described their origin as being Bangladeshi, black Caribbean, Chinese, Indian, Irish or Pakistani. They were the largest seven non-mixed ethnic minority groups living in England as per the 2001 UK census. Participants who described themselves as white British formed the reference group. A total of 13,974 adults, aged 16 years and older, participated in the survey. Of them, we excluded 311 participants because they did not belong to the selected ethnic groups (165 white Europeans and 43 black Africans) or were white British born abroad (n ¼ 103). Of
the 13,663 eligible participants, we further excluded 290 participants because of missing values in one or more of the following variables: ethnicity (n ¼ 218), country of birth (n ¼ 53), year they first moved to the UK (n ¼ 49) and oral health (n ¼ 13). Therefore, the study sample included 13,373 adults with complete data on all relevant variables (97.9% of the 13,663 eligible participants). Variable selection Information on two oral health outcomes, edentulousness and toothache, was collected as part of the interviews in participants' homes. The participants were first asked whether they still have some of their own teeth or have lost them all, and the participants with some remaining teeth were subsequently asked whether they had experienced any toothache in the last 6 months. The prevalence of adults with edentulousness and that of those with toothache were the two outcome measures used for this study. Ethnicity was self-reported as per the participant's family origins, with respondents classified as white British, Irish, black Caribbean, Indian, Pakistani, Bangladeshi and Chinese. Generational status was determined based on the responses given to the questions regarding ethnicity and country of birth. First-generation migrants were nonewhite British participants born abroad, and second-generation migrants were nonewhite British participants born in Great Britain. First-generation migrants were also asked the year they first moved to the UK. This information along with the participants' age at the time of the survey and the survey year was used to estimate two additional indicators of migration history, namely, length of residence and age at arrival. Length of residence in the host country was calculated by subtracting the year they first moved to the UK from the survey year. Age at arrival was calculated by subtracting length of residence from the participants' age. Four measures of socio-economic position (SEP) were chosen to address concerns about their applicability across different ethnic groups. They were education (indicated by the highest formal educational qualification), social class (based on the occupation of the household's head), annual equivalised household income and current economic activity. A composite SEP measure was derived from fitting a one-factor model in confirmatory factor analysis.19 Education, social class, economic activity and income were assigned to a single latent construct representing SEP. Full information maximum likelihood estimation was used to handle nonresponse in SEP measures. As some SEP measures were collected using categorical scales, the weighted least square method was used to estimate model parameters. Factor loadings were all significant and ranged from 0.60 to 0.76. The comparative fit index was 0.99, and the root mean square error of approximation was 0.039, suggesting the model was a good fit to the data. The SEP latent factor score was categorised into quintiles (Q1 ¼ wealthiest, Q5 ¼ poorest).19 Other variables included in the analysis were demographic characteristics (sex and age). Data analyses All analyses were conducted using Stata 15 (StataCorp LP, College Station, TX, USA). Weights were used to account for unequal probability of selection and non-response rates. First- and secondgeneration migrants within each ethnic group were compared against white British (reference group) in terms of demographic factors and the composite measure of SEP using the chi-squared test. The association between generational status and each oral health outcome was assessed in logistic regression models. Odds ratios (ORs) were therefore reported. As there were few cases of edentulousness within some groups (after cross-tabulating
E.K. Delgado-Angulo et al. / Public Health 181 (2020) 53e58
55
first-generation Indian migrants occupied a lower SEP than white British migrants. First- and second-generation Bangladeshi migrants were the most socially disadvantaged group, followed by first-generation black Caribbean and Pakistani migrants. There were large inequalities in edentulousness by generational status. Edentulousness was more common among first-generation black Caribbean and Irish migrants than among white British migrants, whereas edentulousness was less common in all other groups (Table 2). After adjustments for demographic factors and SEP, first-generation black Caribbean (OR: 1.42, 95% CI: 1.11e1.82) and second-generation Pakistani (OR: 3.16, 95% CI: 1.46e6.87) migrants had higher odds of being edentulous whereas firstgeneration Indian (OR: 0.62, 95% CI: 0.45e0.86), Pakistani (OR: 0.62, 95% CI: 0.42e0.93), Bangladeshi (OR: 0.41, 95% CI: 0.28e0.58) and Chinese (OR: 0.49, 95% CI: 0.31e0.77) migrants had lower odds of being edentulous than white British migrants. A different pattern was found for toothache among dentate adults, which was more common in black Caribbean (both generations), Pakistani (both generations), first-generation Bangladeshi, second-generation Irish and first-generation Indian migrants than in white British migrants (Table 3). Toothache was less common among second-generation Bangladeshi migrants. Some of these differences became nonsignificant after adjustment for demographic factors and SEP. In the adjusted model, second-generation Irish (OR: 1.51, 95% CI: 1.25e1.84), first- (OR: 1.61, 95% CI: 1.30e1.99) and secondgeneration black Caribbean (OR: 1.54, 95% CI: 1.20e1.87), firstgeneration Indian (OR: 1.24, 95% CI: 1.03e1.49), and secondgeneration Pakistani (OR: 1.34, 95% CI: 1.04e1.74) migrants had higher odds of having toothache whereas second-generation Bangladeshi migrants had lower odds (OR: 0.51, 95% CI: 0.30e0.86) of having toothache than white British migrants. The interaction between age and generational status was not significant when added to model 1B or 2B. Among first-generation migrants, the mean age at arrival was 20.6 years (SD: 11.4, range: 0e79), and the mean length of residence in the host country was 24.1 years (SD: 13.4, range: 0e79), with large variation between ethnic groups. Irish and black Caribbean migrants were significantly younger at arrival and had lived in the country longer than all Asian groups (Table 4). Both indicators were positively associated with higher odds of being edentulous among all ethnic groups. After adjustments for demographic factors, SEP and the other indicator of migration status, associations remained significant only for black Caribbean, Indian and Pakistani migrants. In these groups, the odds of being edentulous increased
ethnicity with generational status), we used a penalised maximum likelihood estimation to overcome potential issues of complete separation (i.e., a situation where maximum likelihood estimates tend to infinity and thus become inestimable).20 The modelling strategy was first to estimate the crude association of generational status with edentulousness (Model 1A), and then adjust for sex, continuous age and the composite measure of SEP (Model 1B). A two-way statistical interaction (product term) between continuous age and generational status was added to model 1B to test whether the healthy migrant effect varied based on age. A similar set of models was fitted with toothache (models 2A and 2B), although the sample was restricted to dentate adults (n ¼ 12,130). Alternative parameterisations for age were tested in sensitivity analysis (i.e., treating age as a categorical variable or using non-linear forms). Among first-generation migrants, the association of age at arrival and length of residence with each outcome was explored in crude and adjusted models (models 3A and 3B for edentulousness and models 4A and 4B for toothache), stratified by ethnic groups. As age, age at arrival and length of residence are mathematically correlated (length of residence ¼ age e age at arrival), we dealt with collinearity by treating age as a categorical variable (10-year brackets) and the other indicators as a continuous variable. In sensitivity analysis, we included two indicators at a time (continuous age and one of the other indicators). Results Data from 13,373 adults (54% women) were analysed. The participants' mean age was 43.8 years (standard deviation [SD]: 18.0, range: 16e96). Overall, 9.2% (95% confidence interval [CI]: 8.7e9.7) reported being edentulous, and 24.0% (95% CI: 23.2e24.8) of the 12,130 dentate adults reported experiencing toothache in the past 6 months. Participants excluded because of missing data were more likely to be white British than those in the study sample. The sociodemographic composition of the sample by ethnicity and generational status is presented in Table 1. Compared with women among white British migrants, there was a significantly high proportion of women among second-generation black Caribbean migrants and a low proportion among first-generation Pakistani and second-generation Chinese migrants. All second-generation ethnic groups were significantly younger than white British migrants. Among first-generation migrants, Irish and black Caribbean migrants were older, whereas all Asian groups were younger than white British migrants. All groups but second-generation Irish and
Table 1 Sociodemographic characteristics of the sample by ethnicity and generational status. Sociodemographic characteristics
Sample (na) Sex, % Men Women Age (in years) Mean (SD) SEP, % Q1 (wealthiest) Q2 Q3 Q4 Q5 (poorest)
White British
6520
Irish
Black Caribbean
Indian
2nd
1st
2nd
1st
2nd
1st
Pakistani 2nd
1st
Bangladeshi 2nd
1st
Chinese 2nd
1st
774
496
654
634
341
927
408
849
137
954
121
558
45.8 54.2
43.4 56.6
43.8 56.2
40.3 59.7
44.1 56.0
49.9 50.1
48.4 51.6
44.8 55.2
51.4 48.6
47.4 52.6
49.2 50.8
55.0 45.0
43.3 56.7
48.0 (18.5)
42.4 (15.3)
52.1 (18.6)
29.9 (8.3)
55.1 (14.3)
24.9 (7.5)
46.3 (13.9)
23.4 (6.1)
40.1 (13.6)
21.2 (5.1)
36.9 (15.5)
25.3 (11.1)
44.4 (13.4)
24.6 23.8 20.0 17.5 14.1
27.6 24.4 22.0 14.1 11.9
22.3 18.6 20.4 19.6 19.1
16.9 23.6 21.2 17.9 20.4
7.9 15.6 17.3 24.3 34.9
21.8 19.0 26.1 21.4 11.7
21.7 16.4 24.8 20.9 16.2
11.6 12.8 22.1 31.0 22.5
8.9 12.7 19.3 30.8 28.5
2.6 13.1 14.6 28.8 41.0
2.3 4.8 9.7 24.2 58.9
16.2 25.9 26.3 21.8 9.9
23.6 18.7 22.6 19.3 15.9
SEP: socio-economic position; SD: standard deviation. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). a Counts are unweighted.
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Table 2 Models for the association between generational status and edentulousness (n ¼ 13,373 adults). Generational status per ethnic group
White British Irish 2nd Irish 1st Black Caribbean 2nd Black Caribbean 1st Indian 2nd Indian 1st Pakistani 2nd Pakistani 1st Bangladeshi 2nd Bangladeshi 1st Chinese 2nd Chinese 1st
Sample sizea
6520 774 496 654 634 341 927 408 849 137 954 121 558
Edentulousness
Model 1Ab
Model 1Bb
na
%
(95% CI)
ORc (95% CI)
ORc (95% CI)
793 48 100 6 141 3 51 6 33 0 37 1 21
12.2 6.7 17.7 0.7 21.9 0.9 6.1 1.6 4.0 0.0 3.5 1.3 3.6
(11.4e13.0) (4.9e9.1) (14.2e21.9) (0.3e1.7) (18.7e25.4) (0.2e3.9) (4.6e8.1) (0.7e3.9) (2.8e5.7) (0-0) (2.4e5.1) (0.2e8.8) (2.3e5.6)
1.00 0.52 1.54 0.07 2.12 0.07 0.41 0.14 0.30 0.02 0.28 0.13 0.30
1.00 0.98 1.28 0.72 1.42 1.34 0.62 3.16 0.62 0.47 0.41 1.12 0.49
(Reference) (0.40e0.69)*** (1.20e1.98)** (0.03e0.15)*** (1.73e2.60)*** (0.03e0.21)*** (0.31e0.55)*** (0.07e0.28)*** (0.21e0.43)*** (0.00e0.32)** (0.20e0.38)*** (0.04e0.45)** (0.20e0.45)***
(Reference) (0.70e1.39) (0.93e1.75) (0.29e1.78) (1.11e1.82)** (0.42e4.28) (0.45e0.86)** (1.46e6.87)** (0.42e0.93)* (0.03e7.63) (0.28e0.58)*** (0.22e5.80) (0.31e0.77)**
CI: confidence interval; OR: odds ratio. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). *P < 0.05; **P < 0.01; ***P < 0.001. a Counts are unweighted for sample size (N) and people with the outcome (n). b Model 1A was unadjusted. Model 1B was adjusted for sex, continuous age and the composite measure of socio-economic position. c Penalised logistic regression was fitted, and ORs were reported.
Table 3 Models for the association between generational status and toothache in the past 6 months (n ¼ 12130 dentate adults). Generational status per ethnic group
Sample sizea
n White British Irish 2nd Irish 1st Black Caribbean 2nd Black Caribbean 1st Indian 2nd Indian 1st Pakistani 2nd Pakistani 1st Bangladeshi 2nd Bangladeshi 1st Chinese 2nd Chinese 1st
5726 726 395 648 493 338 876 402 816 137 917 120 536
Model 2Ab
Toothache a
1229 212 88 205 154 85 216 108 202 23 225 21 119
c
Model 2Bb
%
(95% CI)
OR (95% CI)
ORc (95% CI)
21.5 29.4 24.8 31.0 31.2 26.4 25.4 28.3 25.3 13.4 25.3 15.4 21.5
(20.4e22.6) (25.8e33.4) (20.0e30.3) (27.4e34.9) (27.0e35.6) (21.4e32.0) (22.2e28.7) (23.8e33.3) (22.3e28.6) (8.5e20.5) (21.9e29.1) (10.0e23.0) (18.1e25.4)
1.00 1.53 1.21 1.65 1.66 1.31 1.24 1.44 1.24 0.57 1.24 0.67 1.00
1.00 1.51 1.21 1.54 1.61 1.25 1.24 1.34 1.19 0.51 1.13 0.64 0.99
(Reference) (1.26e1.85)*** (0.91e1.60) (1.37e1.98)*** (1.34e2.04)*** (0.99e1.73) (1.03e1.49)* (1.13e1.84)** (1.04e1.48)* (0.34e0.94)* (1.01e1.51)* (0.41e1.10) (0.80e1.26)
(Reference) (1.25e1.84)*** (0.91e1.60) (1.20e1.87)*** (1.30e1.99)*** (0.94e1.68) (1.03e1.49)* (1.04e1.74)* (0.99e1.43) (0.30e0.86)* (0.91e1.40) (0.39e1.06) (0.79e1.24)
CI: confidence interval; OR: odds ratio. 1st and 2nd refer to first- and second-generation migrants (foreign- and UK-born, respectively). *P < 0.05; **P < 0.01; ***P < 0.001. a Counts are unweighted for sample size and people with the outcome (n). b Model 2A was unadjusted. Model 2B was adjusted for sex, continuous age and the composite measure of socio-economic position. c Logistic regression was fitted, and ORs were reported.
by around 1.10e1.21 times per year increase in age at arrival and by around 1.11e1.27 times per year increase in length of residence. Contrarily, neither age at arrival nor length of residence was significantly associated with toothache among first-generation dentate migrants. Similar findings were obtained in sensitivity analysis (using continuous age and either of the two indicators).
Discussion This study provides mixed support to the healthy migrant effect on oral health among adults in England, with marked variations based on the ethnic groups and oral health outcomes. The odds of being edentulous converged to those of the host population among all Asian groups, with evidence of an ‘overshoot’ (second-generation migrants worse than white British migrants) among Pakistani migrants. The healthy migrant effect was not evident for toothache. All migrant groups but second-generation Bangladeshi migrants had either higher or similar odds of reporting toothache than white British migrants.
The large variation seen across ethnic groups implies that the findings cannot be entirely attributed to self-selection into migration. Alternative explanations include the social determinants of health and acculturation, which might interact with each other to affect migrants' oral health.10,21 Although we controlled for current SEP, social circumstances in the sending country are also important as they will affect migrants' health throughout the life course (before, during and after relocation).9,10 Once in the new country, migrants may be subject to racism and discrimination,22,23 with the emerging literature linking both to oral health.24 Policies to improve access to health care might also be important for migrants' oral health, with evidence from the US suggesting that having health insurance could mitigate inequalities between non-citizens and natives.16 In this regard, edentulousness could be considered a sequel of having access to Western dentistry for longer time span (among first-generation migrants) or for a lifetime (among white British and second-generation migrants). As for cultural explanations, migrants may arrive with more favourable behaviours than those practised by the host population. Oral conditions have a strong behavioural component. Aside from
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57
Table 4 Models for the association of age at arrival and length of residence with oral health outcomes among first-generation migrants by ethnicity. Ethnicity
Edentulousness Meand
(95% CI)
Model 3Aa b
Toothache
Model 3Ba
Meand
(95% CI)
b
Model 4Aa b
Model 4Ba
OR (95% CI)
ORb (95% CI)
(13.9e16.1) (27.7e30.0)
0.98 (0.97e1.00) 0.98 (0.95e1.01)
0.92 (0.84e1.02) 0.92 (0.83e1.02)
15.7 28.2
(14.9e16.4) (27.4e29.0)
1.00 (0.98e1.02) 1.00 (0.98e1.02)
1.01 (0.93e1.09) 1.01 (0.93e1.09)
1.10 (0.97e1.25) 1.12 (0.99e1.27)
20.5 23.3
(19.8e21.2) (22.6e24.0)
1.02 (1.00e1.03) 1.00 (0.98e1.02)
0.98 (0.92e1.05) 0.98 (0.92e1.04)
1.09 (1.05e1.13)*** 1.08 (1.05e1.11)***
1.21 (1.04e1.40)* 1.21 (1.05e1.40)**
21.0 22.9
(20.3e21.7) (22.2e23.6)
1.02 (1.00e1.03) 1.01 (0.99e1.03)
0.98 (0.92e1.05) 0.97 (0.91e1.04)
(21.5e23.1) (20.7e22.3)
1.11 (1.08e1.14)*** 1.07 (1.04e1.09)***
1.17 (1.03e1.34)* 1.17 (1.03e1.34)*
22.3 21.6
(21.4e23.1) (20.8e22.4)
1.04 (1.02e1.06) 1.02 (1.00e1.04)
1.03 (0.96e1.11) 1.01 (0.94e1.08)
(21.9e23.3) (20.5e21.9)
1.07 (1.03e1.12)** 1.09 (1.06e1.12)***
0.97 (0.80e1.18) 0.99 (0.82e1.20)
22.5 21.4
(21.8e23.2) (20.7e22.1)
1.01 (0.99e1.03) 1.01 (0.99e1.03)
0.99 (0.91e1.08) 0.99 (0.91e1.08)
OR (95% CI)
OR (95% CI)
(12.6e14.7) (29.2e31.3)
1.10 (1.07e1.12)*** 1.05 (1.02e1.07)**
1.04 (0.94e1.14) 1.04 (0.93e1.15)
15.0 28.9
(15.1e16.5) (27.3e28.7)
1.14 (1.09e1.18)*** 1.12 (1.09e1.15)***
1.10 (1.00e1.21)* 1.11 (1.01e1.21)*
(20.3e21.7) (22.2e23.6)
1.06 (1.03e1.09)** 1.11 (1.09e1.14)***
(20.4e21.8) (22.1e23.4)
c
Irish (n ¼ 449 and 391) Age at arrival 13.6 Length of residence 30.2 Black Caribbean (nc ¼ 594 and 492) Age at arrival 15.8 Length of residence 28.0 Indian (nc ¼ 950 and 871) Age at arrival 21.0 Length of residence 22.9 c Pakistani (n ¼ 783 and 800) Age at arrival 21.1 Length of residence 22.7 Bangladeshi (nc ¼ 1158 and 905) Age at arrival 22.3 Length of residence 21.5 c Chinese (n ¼ 580 and 503) Age at arrival 22.6 Length of residence 21.2
CI: confidence interval; OR: odds ratio. *P < 0.05; **P < 0.01; ***P < 0.001. a Model A was unadjusted. Model B was adjusted for sex, age (categorical), the composite measure of socio-economic position and the other indicator of migration status. b Penalised logistic regression was fitted for edentulousness and logistic regression for toothache. ORs were reported in both cases. c Number of first-generation migrants for models of edentulousness and toothache, respectively. d Predicted means derived from linear models regressing age at arrival/length of residence on sex, continuous age and the composite measure of socio-economic position.
lower smoking rates,25 diets are generally healthier in sending countries (less availability of ready-to-eat meals and foods high in free sugars), which last until internalisation of the new culture and lifestyles occurs.26 In addition, the availability of social networks in the receiving country could provide emotional and instrumental support to migrants.3,11 There is evidence that members of minority ethnic groups are healthier when living in enclaves of their own ethnic group, the so-called ethnic density effect.27,28 The findings among the black Caribbean and Irish migrants in this study did not conform to the healthy migrant hypothesis. Black Caribbean migrants had worse oral health and Irish migrants were not different than the white British population. However, these patterns are not specific to oral health.12,29 Black Caribbean migrants often exhibit worse health than the white population in England, even among second-generation migrants despite relative improvements in social and economic circumstances compared with first-generation migrants.30 Contrary to migration from Commonwealth countries, which happened to address a need for labour after World War II, Irish people have a longer history of migration. Although the first cohorts of Irish migrants were typically in worse health than the host population, new Irish cohorts either born in or moving to England are healthier.29 A number of factors could help explain the different findings with edentulousness and toothache. Edentulousness is a cumulative condition resulting from history of dental diseases, access to dental care, and people's attitudes and behaviours as well as those of the dentist.31 On the contrary, toothache is a transient condition that can sometimes be managed without a visit to the dentist. This is in addition to physiological differences in experimentally induced pain between ethnic groups, with ethnic minority groups having high pain sensitivity, lower pain tolerance but similar pain thresholds than whites.32 Edentulousness is also almost exclusively a condition of older people. First-generation black Caribbean migrants in this study were older, whereas all Asian groups were younger than the white British population. We controlled for age in all regression models, and our findings were unchanged when using alternative age parameterisations. We did not find a
significant interaction between age and generational status either. Although residual confounding cannot be ruled out, we are confident that our findings reflect more than just model misspecification. Furthermore, data on toothache were collected among dentate adults only, which could have made ethnic groups more homogenous as those with the worst oral health (edentulous) had already been excluded. The use of nationally representative data and the large sample size for the main minority ethnic groups in England are strengths of this study. However, this study is not without limitations. First, using cross-sectional data limited our ability to establish temporal order between variables. This is relevant for edentulousness, which could have occurred before migration. Second, we used relatively old data. However, HSE 1999 remains the most recent health survey of ethnic minorities with oral health data in England. The HSE 2004 included the latest ethnic boost sample, but it did not include any oral health data. In addition, the latest Adult Dental Health Survey, carried out in 2009, did not collect data on migration status. That said, although it is unlikely that oral health inequalities by ethnicity and migration status had changed in such a short time, data from emerging minority ethnic groups in England, such as black Africans and Eastern Europeans, could not be included in the present analysis. Third, some may question the validity of self-reports on edentulousness. However, self-reports were found valid when compared against clinically determined tooth loss.33,34 Indeed, the proportion of edentulous adults in this study was similar to that reported for England in the 2009 Adult Dental Health Survey. Further research would benefit from using broader frameworks emphasising the social determinants of health in both sending and receiving countries.7,9,11 Upon arrival, a better understanding is needed on how the new social context modifies the assimilation of migrants to the new culture and its subsequent impact on oral health.21 Qualitative life history research exploring the experiences of first- and second-generation migrants in relation to oral health, dental behaviours and diet would also enable us to better explain the nuances of the data. These strategies could help unravel some of the push and pull factors behind families' decision to relocate.
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Conclusion This study found mixed evidence for the healthy migrant effect on adult oral health in England. The healthy migrant effect was more consistently observed for edentulousness and among Asian groups. Black Caribbean people had the worst oral health when compared with the white British population. Author statements Ethical approval This is a secondary analysis of a national survey with ethical approval; no ethical approval was sought for this study. Funding No funding has been received for this research. Competing interests The authors have no competing interests. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.puhe.2019.11.025. References 1. Roura M. Unravelling migrants' health paradoxes: a transdisciplinary research agenda. J Epidemiol Community Health 2017;71:870e3. 2. 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;26:367e97. 3. Shor E, Roelfs D, Vang ZM. The "Hispanic mortality paradox" revisited: metaanalysis and meta-regression of life-course differentials in Latin American and Caribbean immigrants' mortality. Soc Sci Med 2017;186:20e33. 4. Vang ZM, Sigouin J, Flenon A, Gagnon A. Are immigrants healthier than nativeborn Canadians? A systematic review of the healthy immigrant effect in Canada. Ethn Health 2017;22:209e41. 5. Moullan Y, Jusot F. Why is the 'healthy immigrant effect' different between European countries? Eur J Public Health 2014;24:80e6. 6. Constant AF, Garcia-Munoz T, Neuman S, Neuman T. A "healthy immigrant effect" or a "sick immigrant effect"? Selection and policies matter. Eur J Health Econ 2018;19:103e21. 7. Jasso G, Massey DS, Rosenzweig MR, Smith JP. Immigrant health: selectivity and acculturation. In: Anderson NB, Bulatao RA, Cohen B, editors. Critical perspectives on racial and ethnic differences in health in late life. Washington DC: National Academy Press; 2004. p. 227e66. 8. Markides KS, Rote S. The healthy immigrant effect and aging in the United States and other western countries. Gerontol 2019;59:205e14. 9. Spallek J, Zeeb H, Razum O. What do we have to know from migrants' past exposures to understand their health status? a life course approach. Emerg Themes Epidemiol 2011;8:6.
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