Selective migration and mortality by economic status in Lolland-Falster, Denmark, 1992–2018

During the past 30 years, a mortality gap developed between Lolland-Falster (the rural-provincial southeastern part) and the rest of Denmark. A main driver was selective in-migration of Danes with a high risk of death, especially of working-ages. In the present study, we determined the role of economic status in this selective in-migration. We used individual-level data from the Central Population Register and data on income source; self- or publicly supported. The study population included people aged 30–64 and living in Denmark at any time between 1992 and 2018. Mortality rate ratios (MRR) were calculated using Poisson regression for three time-periods: 1992–1999, 2000–2009 and 2010–2018. Two in five in-migrants to Lolland-Falster were people on public support. In 2010–2018, they had an MRR of 8.71 (95% confidence interval (CI): 8.05–9.42) compared with self-supported people, and an MRR of 1.49 (95% CI: 1.38–1.61) compared with publicly supported people elsewhere in Denmark. In-migration of working-aged people on public support was a main contributor to the excess mortality in Lolland-Falster as compared with the rest of Denmark. To understand urban–rural differences in health, population movements and national income patterns are important to take into account.