Long-term trends in urban-neighbourhood inequalities in cause-specific mortality and hospitalisation – multilevel analyses among individuals nested in Finnish post-code areas, 1991–2018

BACKGROUND: High-income countries yield mixed evidence concerning the long-term trends of neighbourhood inequalities in health outcomes. The reasons why these inequalities persist and the factors driving any changes over time remain unclear. We analysed trends in general neighbourhood differences in mortality and hospitalisation, compared specific area-level and individual-level income effects, and assessed whether area-level effects were attributable to the neighbourhood population composition. METHODS: This prospective cohort study used individual-level register-linked information on sociodemographic factors covering the total population of 20–64-year-olds living in Finnish cities at the beginning of seven four-year periods in 1991–2018 (N = 952,493–1,200,431). We used random-effects Poisson models to assess all-cause and external mortality and hospitalisations among individuals nested in postal-code areas. RESULTS: The general contextual effect of the neighbourhood on all-cause mortality and hospitalisation was stable across time, with a median incidence-rate ratio of around 1.20–1.30, and it was mainly attributable to the population's composition. The association between area-level income and both mortality and hospitalisation was also robust and increased slightly even after accounting for population composition. The lowest neighbourhood income quintile in 2015–2018 had 15% (95% CI:5–26%) and 30% (95% CI:15–47%) excess mortality among men and women, respectively. These differentials were particularly large for external causes, but all area-level income associations were much smaller than the corresponding individual-level associations. CONCLUSION: The overall relevance of the neighbourhood context to mortality and hospitalisation was stable across time, and generally attributable to population composition. However, there were substantial relative area-level income disparities between neighbourhoods, which had grown over time.