Statistical agencies and health researchers require summary metrics of mortality to make sense of the fine-grained information collected at the individual level. These metrics serve four key roles: to set health targets, to compare populations, to uncover emerging threats, and to evaluate policy outcomes. Typically, the metrics used for such purposes summarize average outcomes, such as life expectancy at birth or age-standardized death rates. Overlooked are inequalities in mortality within populations, which are both substantial and changing over time.
Lifespan inequality (also known as age-at-death variation) is a metric of how ages at death are spread out across individuals. At the population level, lifespan inequality indicates heterogeneity in population health. This heterogeneity is important to consider when designing health and welfare policies, including equitable pension schemes. At the individual level, lifespan inequality measures the uncertainty in the timing of death. Economic models have shown that individuals are highly risk averse when it comes to survival and would prefer to live in a society with a lower life expectancy if they could increase the certainty that they would survive to such an age. While life expectancy captures the magnitude of survival improvement, lifespan inequality is its complement, capturing the equality in survival improvement across different age ranges. A full picture of population health requires us to monitor both.
The Lifespan Inequalities research group, funded by a starting grant from the European Research Council, is conducting the most comprehensive inquiry to date into the development and causes of lifespan inequality. Specifically, our research has four main objectives:
1. To track and forecast the relationship between life expectancy and lifespan inequality in national populations.
2. To determine the ages and causes of death that drive outlying age patterns of mortality.
3. To analyze the development of lifespan inequality by socioeconomic groups.
4. To assess the impact of individual differences in behavior on lifespan inequality.
All projects have the potential to uncover novel results with important policy implications. The first objective is descriptive and addresses the degree to which there is added value in monitoring lifespan inequality. The remaining objectives address how and why populations and socioeconomic groups differ in lifespan inequality – this comparative perspective allows us to identify best practices in reducing inequalities across populations.