Explaining the migrant-native mortality gap: a decomposition analysis for São Paulo, Brazil

Comparisons of mortality patterns between foreign-born and native-born adults in high-income countries have suggested that migrants experience lower mortality than the host populations. However, migrant mortality advantage is not universal and might not reflect the health outcomes of foreign-born adults living in developing countries. Previous studies conducted in the Brazilian State of São Paulo found mortality disadvantages among foreign-born adults compared to other residents, even after controlling for age, sex, and education. However, the contribution of each compositional trait to explain the migrant-native mortality gap in São Paulo remains unclear. In this study, we apply the decomposition algorithm proposed by Das Gupta to investigate the contribution of two key factors – age and education – in explaining the migrant-native mortality gap in São Paulo, Brazil. The results showed an overall CDR for foreign-borns of 37.37 per thousand and 10.91 per thousand for native-born individuals, giving a total difference of 26.42. We found that more than 93% of the migrant-native mortality gap is explained by differences in the age composition of these two subgroups. This effect is concentrated at older ages. Differences in the educational composition of migrants and non-migrants contributed to narrowing the total difference by 0.90 points or 3%. Individuals with low education were the ones who contributed to reducing the mortality gap at all ages, especially at older ages. Although the “education effect” played a role in attenuating the mortality differences between foreign-born and native-born adults, its magnitude was quite neglectable compared with the age effect.