Wealth and mortality among late-middle-aged individuals in Norway: a nationwide register-based retrospective study

In recent decades, we have observed rising wealth inequality while the pace of growth of life expectancy has slowed in many Western welfare democracies. There is scarce evidence, however, on links between wealth and mortality. The main methodological limitation in this area of scholarship is its inability to account for individuals' unobserved heterogeneity, such as personality and genetic factors, which could potentially affect both their wealth level and survival probabilities. This study aims to explore how wealth is linked to mortality risk in late-middle age, providing insights into the broader implications of socioeconomic status on health outcomes.

In this study, we use high-quality register data on wealth and mortality for the entire population of Norway, one of the world's most advanced welfare states with a low income inequality level but a highly uneven distribution of wealth. We address some of the main methodological constraints of the previous research by exploring if wealth at the age of 37-38 predicts mortality up to age 62. The research design employed mitigates the problem of unobserved heterogeneity by using sibling and twin fixed-effects models.

Both Kaplan-Meier survival analyses and the Cox proportional hazard regression results suggest that wealth is an important predictor of mortality even after individuals' observed and unobserved characteristics are accounted for with hazard ratios of 2.39 [95% confidence interval, CI 2.02, 2.83] among men and 1.74 [95% CI 1.39, 2.16] among women for the inverted cumulative density rank coefficients. The most disadvantaged groups are non-partnered men and women at the lower end of wealth distribution. Twin analyses align with the findings for the general population, indicating that wealth's effect on mortality is not confounded by genetic or shared family background factors.

Our findings suggest that wealth is an important predictor of mortality, even in an advanced welfare state with comprehensive healthcare provisions, highlighting the need to address inequalities in wealth distribution to improve population health outcomes.

The Research Council of Norway.