Four things the ONS Longitudinal study has taught us about immigration and health

• Listen to the Linking our Lives Podcast episode with Matt Wallace and Joe Harrison who helped author this blog

Since 1971, the ONS Longitudinal Study has shed light on a huge range of social issues: this series of Linking our Lives blogs looks back on the major contributions which have been made to different fields of research using this unique data resource. This blog is the second in the series, and highlights some of the key ways in which this one per cent sample of the population of England and Wales, which contains census and life event data on more than a million people, has contributed to the study of links between immigration and health. The series aims to highlight the breadth of further research which will become possible when the 2021 Census link to the study is finalised in 2025.

1. Why are death rates lower among immigrant populations?

Research over the past 40 years has shown those who migrate internationally tend to have lower death rates compared to non-migrants born in their destination countries, but until the early 2000s few studies had examined this phenomenon over the long term. Seeromanie Harding’s 2003 study of immigrants to England and Wales from the Indian Subcontinent used LS data from 1971 to 2000 to show that this advantage lessened with time and that the group’s death rates tended to rise with the number of years of residence here. Matt Wallace took this work further, first with a 2014 study which used LS data to ask if inaccuracies in, or missing, emigration data could account for the effect, and which found they could not. Most groups of international migrants had lower death rates than non-migrants of England and Wales, he found. In a further paper, he showed high death rates from infectious diseases among these groups was more than offset by low death rates from chronic diseases and from cancers compared to non-migrants. Later he asked if the ‘salmon bias effect,’ in which those suffering ill health return to their place of birth, could explain the effect but found that it could not.

2. Low mortality, poor health?

In 2020 Matt Wallace and Fran Darlington-Pollock examined the idea that links between health and mortality might be weaker among migrants compared to non-migrants. They suggested that despite having low death rates, some immigrant groups were more likely to report being in poor health than non-immigrants were. They used the LS to compare health and mortality data over 20 years and found evidence of higher self-reported levels limiting long-term illness combined with low death rates (compared to non-migrants) among those from three areas: Pakistan and Bangladesh, India and the Caribbean. They suggested the finding might be explained by selection effects – that migrants may have a higher incidence of long-term illnesses than non-migrants do, but a better chance of survival – and cultural factors such as diet, as well as differences in the ways migrant groups evaluate their own health.  Some of these issues will be examined in a project named ‘Living longer in poorer health? Understanding the immigrant morbidity-mortality paradox’ (PARA-MOR), which will be led by Matt Wallace at the Centre for Research on Inclusive Society (CRIS) at the University of Salford. The £1.3 million UKRI study will try to understand better the causes and the consequences of why international migrants are living longer lives in worse health than non-migrants. The project will use cutting-edge methods to analyse large-scale longitudinal data on illness and mortality from various high-income countries.

3. Health and mortality among the descendants of immigrants

In light of these findings, researchers used the LS to investigate whether lower mortality extended to the children and grandchildren of immigrants. Early work on the subject included a 1996 study by  Seeromanie Harding and R Balarajan, which looked at the deaths of around 1500 second generation Irish people in England and Wales between 1971 and 1989. It found mortality rates higher than those in the general population, influenced by socioeconomic, cultural and lifestyle factors. They followed this in 2001 with research on third generation Irish people in England and Wales, which showed that although socioeconomic disadvantage lessened between generations, mortality remained high. Further work by Anne Scott and Ian Timaeus found UK-born Black Caribbeans had higher death rates than UK-born Whites, though this was accounted for by low socioeconomic status.

Seeromanie Harding and R Balarajan also looked at limiting long-term illness among Black Caribbeans, Black Africans, Indians, Pakistanis, Bangladeshis and Chinese born in the UK. They found higher rates of such illness for all groups apart from Chinese, and noted that Black Africans born here had higher rates than those born in Africa. Little was known about the health consequences of being a second or third generation migrant, the research said.

In 2015, Matt Wallace asked whether a migrant mortality advantage persisted beyond the first generation. As a single group, UK-born ethnic minorities (the descendants of migrants) had higher death rates than both migrants and UK-born Whites in England and Wales. After adjusting for disadvantages in socioeconomic factors like occupation, education, and housing, the death rate of UK-born ethnic minorities became comparable to the death rate of the UK-born White group. When examining variation by background, Matt Wallace found higher death rates among UK-born Black Caribbeans, UK-born Pakistanis and Bangladeshis, and the UK-born “Black other” group. However, only UK-born Black Caribbeans continued to have high death rates after adjusting for socioeconomic status.

4. Cancer incidence among immigrants and their descendants

In 1999 Seeromanie Harding and Michael Rosato compared the incidence of cancer between 1971 and 1989 among those who were living in England or Wales but were born in Scotland, Northern Ireland, the Irish Republic, Caribbean Commonwealth or the Indian subcontinent. They found the incidence of the main forms of the disease was lower among West Indians and South Asians, but higher in some cases among those from Scotland and Ireland. In 2009 Harding and colleagues followed this with research using mortality data from the 1970s, 1980s and 1990s, showing that in spite of general declines in cancer death rates, inequalities in migrant mortality remained – and in some cases led to growing disparities between migrant groups and the wider population. Research by Joseph Harrison published in 2024 has updated and expanded on these findings, revealing that cancer incidence and mortality remains lower among Pakistani-born and Bangladeshi-born people in England and Wales, and also for their descendants – though the likelihood of survival after diagnosis may be lower in descendants. 

References:

Harding, S. (2001). Mortality of third generation Irish people living in England and Wales: longitudinal study. BMJ, 322(7284), pp.466–467. doi:https://doi.org/10.1136/bmj.322.7284.466.

Harding, S. (2003). Mortality of migrants from the Indian subcontinent to England and Wales: effect of duration of residence. Epidemiology (Cambridge, Mass.), [online] 14(3), pp.287–92. Available at: https://pubmed.ncbi.nlm.nih.gov/12859028/.

Harding, S. and Balarajan, R. (1996). Patterns of mortality in second generation Irish living in England and Wales: longitudinal study. BMJ, 312(7043), pp.1389–1392. doi:https://doi.org/10.1136/bmj.312.7043.1389.

Harding, S. and Balarajan, R. (2000). Limiting Long-term Illness Among Black Caribbeans, Black Africans, Indians, Pakistanis, Bangladeshis and Chinese Born in the UK. Ethnicity & Health, 5(1), pp.41–46. doi:https://doi.org/10.1080/13557850050007338.

Harding, S. and Rosato, M. (1999). Cancer Incidence Among First Generation Scottish, Irish, West Indian and South Asian Migrants Living in England and Wales. Ethnicity & Health, 4(1-2), pp.83–92. doi:https://doi.org/10.1080/13557859998218.

Harding, S., Rosato, M. and Teyhan, A. (2009). Trends in cancer mortality among migrants in England and Wales, 1979–2003. European Journal of Cancer, 45(12), pp.2168–2179. doi:https://doi.org/10.1016/j.ejca.2009.02.029.

Harrison, J., Sullivan, F., Keenan, K. and Hill Kulu (2024). All-cancer incidence and mortality in Pakistanis, Bangladeshis, and their descendants in England and Wales. BMC Public Health, 24(1). doi:https://doi.org/10.1186/s12889-024-20813-1.

Schofield, L., Walsh, D., Feng, Z., Buchanan, D., Dibben, C., Fischbacher, C., McCartney, G., Munoz-Arroyo, R. and Whyte, B. (2019). Does ethnic diversity explain intra-UK variation in mortality? A longitudinal cohort study. BMJ Open, 9(3), p.e024563. doi:https://doi.org/10.1136/bmjopen-2018-024563.

Scott, A.P. and Timæus, I.M. (2013). Mortality differentials 1991−2005 by self-reported ethnicity: findings from the ONS Longitudinal Study. Journal of Epidemiology and Community Health, 67(9), pp.743–750. doi:https://doi.org/10.1136/jech-2012-202265.

Taylor, H., Bécares, L., Kapadia, D., Nazroo, J., Stopforth, S. and White, C. (2024). Ethnic inequalities in mortality in England and Wales: examining life expectancy data and methods. [online] Available at: https://kclpure.kcl.ac.uk/ws/portalfiles/portal/299821661/Ethnic_Inequalities_in_Mortality_in_England_and_Wales_MPO_FINAL.pdf[Accessed 9 Dec. 2024].

Wallace, M. (2016). Adult mortality among the descendants of immigrants in England and Wales: does amigrant mortality advantagepersist beyond the first generation? Journal of Ethnic and Migration Studies, 42(9), pp.1558–1577. doi:https://doi.org/10.1080/1369183x.2015.1131973.

Wallace, M. and Darlington‐Pollock, F. (2020). Poor health, low mortality? Paradox found among immigrants in England and Wales. Population, Space and Place, 28(3). doi:https://doi.org/10.1002/psp.2360.

Wallace, M. and Kulu, H. (2014). Low immigrant mortality in England and Wales: A data artefact? Social Science & Medicine, 120(120), pp.100–109. doi:https://doi.org/10.1016/j.socscimed.2014.08.032.

Wallace, M. and Kulu, H. (2015). Mortality among immigrants in England and Wales by major causes of death, 1971–2012: A longitudinal analysis of register-based data. Social Science & Medicine, 147, pp.209–221. doi:https://doi.org/10.1016/j.socscimed.2015.10.060.

Wallace, M. and Kulu, H. (2018). Can the salmon bias effect explain the migrant mortality advantage in England and Wales? Population, Space and Place, 24(8), p.e2146. doi:https://doi.org/10.1002/psp.2146.