Assessing the Effects of Health-Selective Internal Migration on Spatial Inequality in the United States: A Simulation-Based Analysis

Abstract

Background: There are vast geographic and racial disparities in disability prevalence across the United States. Some geographic inequalities may be artifacts of health-selective internal migration, and it is unclear to what extent this migration influences the association between local characteristics and health outcomes. Accurately identifying the causes of disability is crucial to develop policies that reduce disparities in disability prevalence. Aims: This study measured how much internal migration contributes to spatial patterns of disability prevalence in the United States for the whole population and separately for five racial-ethnic groups. Methods: We ran a microsimulation of the US population aged 45 years and above and produced age-standardized estimates of disability prevalence in 976 substate locations between 2012 and 2019. By comparing patterns of disability prevalence with and without migration, we demonstrated the influence of migration on spatial inequality for the whole population and five racial-ethnic groups. Migration in the simulation was parameterized using generalized linear mixed effects models fit on the American Community Survey Public Use Microdata Sample. Additional parameters were derived from the National Health Interview Survey and previously published estimates. Results: We found that adults with disabilities were more likely to move compared to those without disabilities (3.4% vs 2.7% annually). Migration affected the prevalence of disability in most locations, but the effect was highly variable. The mean absolute difference in location-specific disability prevalence in 2019 with migration compared to the scenario without migration was 0.9 percentage points, with a mean absolute relative difference of 2.8%. Migration marginally increased the variation in disability prevalence across locations. Migration slightly exacerbated inequalities for minoritized racial-ethnic groups across areas classified by urbanicity and median income, although this pattern was not found for the White population or the total population. Conclusion: Disability is associated with whether and where adults move in the United States. However, health-selective internal migration does not substantially alter the spatial distribution of disability prevalence in the United States and only slightly affects the association between area-level income or urban-rural classification and disability prevalence. Nonetheless, migration meaningfully increased or decreased the disability prevalence in some areas, especially for minoritized racial-ethnic groups, so analyses of spatial inequality should consider the influence of migration on disability prevalence.