Migration and health
Do cardiometabolic, behavioural and socioeconomic factors explain the ‘healthy migrant effect’ in the UK? Linked mortality follow-up of South Asians compared with white Europeans in the Newcastle Heart Project
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We thank Timaeus and Scott for drawing readers' attention to our interpretation(1) of their data which differs from their own(2) (rapid response 28/7/2017). We are glad to explain our thinking especially as the issues go beyond their data and to the concepts and the UK quantitative evidence. We agree that in their paper after adjustment for three socio-economic and an area of residence variables the mortality rate ratios are lower in South Asian groups than in the White group.(2) The explanation for our different interpretation is that we placed emphasis on their model adjusting mortality for age, sex and period while they emphasised the results of models further adjusting for socio-economic status and residence.(2)
Generally the ‘healthy migrant effect’ is considered as unexpected and hence a paradox because immigrant populations sometimes have better health, most usually mortality, despite their socio-economic and other disadvantages.(3, 4) It is not generally understood as an effect that arises after adjustments for socio-economic and other related factors. In Timaeus and Scott’s model 1 the rate ratios for Indian, Pakistani and Bangladeshi populations born abroad and participating in the Longitudinal Study in England and Wales are shown in their table 5 and were 0.91, 0.95 and 1.01 with the 95% confidence intervals all including the reference value of 1. In model 1, the point estimates of the rate ratios for the same ethnic groups born in the UK were simil...Show More
Hayes et al.  repeatedly cite a 2013 article by Scott and Timæus , also published in this journal, as having ‘not found a healthy migrant effect in South Asians’ and as providing ‘little evidence of a South Asian mortality advantage’. This contradicts our own interpretation of the results that we presented in that paper. We concluded that ‘Immigrants are selected for good health’. Moreover, with specific reference to South Asians, we stated that: ‘adjusted for SES and residence, … Indian, Pakistani, [and] Bangladeshi … immigrants all had lower mortality than UK-born Whites who were living in similar circumstances to them … This suggests that immigrants from the Indian subcontinent … are … selected for health’.
We think it regrettable that Hayes et al. do not indicate to readers of their paper that their interpretation of the results in our paper is almost diametrically opposed to our own. Moreover, they provide no explanation whatsoever of why they came to the view that we had misinterpreted our results.
Our study investigated all-cause mortality at ages 1−79 in 1991−2005 by self-reported ethnicity and country of birth. The data were from the Office for National Statistics Longitudinal Study of England and Wales for the cohort aged 0−64 in 1991. Poisson regression was used to adjust the estimates for metropolitan residence and three indicators of socioeconomic status. In the fully-adjusted model, but not the model that adjusted only for age, sex and per...Show More