Migration associated with allergic disease among ethnic groups in the Netherlands

Intercontinental migration showed a positive association with allergies among adults from ethnic groups living in Amsterdam, the Netherlands, compared with participants of Dutch origin, according to a letter published in Allergy.

Abena S. Amoah, BA, MSc, PhD, assistant professor in the department of population health, faculty of epidemiology and population health at London School of Hygiene and Tropical Medicine, and colleagues examined data from the population-based Healthy Life in an Urban Setting study.

The analysis included 21,850 individuals of Dutch (n = 4,564; 20.9%), Surinamese (n = 7,427; 34%), Turkish (n = 3,614; 16.6%), Moroccan (n = 3,906; 17.9%) and Ghanaian (n = 2,339; 10.7%) origin. Also, 13,451 (61.6%) of these individuals represented the first generation of these ethnic groups and 3,835 (17.6%) represented the second generation.

Overall, 22.7% of participants reported nasal allergy, with significantly higher rates among first-generation (22.1%) and second-generation (27.1%) groups compared with the Dutch origin group (20.5%).

Similarly, 10.5% of the overall population reported asthma, including rates of 10.1% among the first-generation group and 14.2% in the second generation, which the researchers called significantly higher than the 8.6% rate among participants of Dutch origin.

Compared with the first-generation group, the second-generation group appeared significantly more likely to have nasal allergy (adjusted OR [aOR] = 1.15; 95% CI, 1.02-1.31), asthma (aOR = 1.82; 95% CI, 1.54-2.15) and eczema (aOR = 1.28; 95% CI, 1.06-1.54) in the previous 12 months, but not food allergy (aOR = 1.22; 95% CI, 0.99-1.51) or chronic rhinosinusitis (aOR = 0.88; 95% CI, 0.69-1.12).

The first generation also experienced an inverse association between increasing age at the time of migration and nasal allergy (aOR = 0.99; 95% CI, 0.98-0.99) and asthma (aOR = 0.99; 95% CI, 0.98-0.99).

But the researchers did not find any association between increasing age at the time of migration and eczema (aOR = 0.99; 95% CI, 0.98-1), food allergy (aOR = 1; 95% CI, 0.99-1.02) or chronic rhinosinusitis (aOR = 1; 95% CI, 0.99-1.01).

Longer residence in the Netherlands appeared significantly associated with nasal allergy (aOR = 1.01; 95% CI, 1-1.02) and asthma (aOR = 1.01; 95% CI, 1-1.02), with a borderline association with eczema (aOR = 1.01; 95% CI, 0.99-1.02).

There was no significant association, though, between longer residence and food allergy (aOR = 0.99; 95% CI, 0.98-1.01) or chronic rhinosinusitis (aOR = 1; 95% CI, 0.99-1.01).

The researchers called their findings consistent with previous studies showing higher allergy burdens among individuals who were born to foreign-born parents compared with host populations and first-generation individuals.

These findings also may indicate that older immigrants may have had greater exposure to protective factors in their countries of origin before migration. Studies of the epigenomic profiles of migrant and host populations could reveal the mechanics of these disease risks, the researchers wrote.

The researchers also recommended further studies of other large ethnic groups in the Netherlands including individuals of Indonesian, German or Polish ethnic origin and studies of changes in the epigenome, microbiome, systemic inflammation and other underlying mechanisms.