The Cross-sectional Average Inequality in Lifespan (CAL†): A Lifespan Variation Measure That Reflects the Mortality Histories of Cohorts

Abstract

Lifespan variation is a key metric of mortality that describes both individual uncertainty about the length of life and heterogeneity in population health. We propose a novel and timely lifespan variation measure, which we call the cross-sectional average inequality in lifespan, or CAL†. This new index provides an alternative perspective on the analysis of lifespan inequality by combining the mortality histories of all cohorts present in a cross-sectional approach. We demonstrate how differences in the CAL† measure can be decomposed between populations by age and cohort to explore the compression or expansion of mortality in a cohort perspective. We apply these new methods using data from 10 low-mortality countries or regions from 1879 to 2013. CAL† reveals greater uncertainty in the timing of death than the period life table–based indices of variation indicate. Also, country rankings of lifespan inequality vary considerably between period and cross-sectional measures. These differences raise intriguing questions as to which temporal dimension is the most relevant to individuals when considering the uncertainty in the timing of death in planning their life courses.

Trends in mortality patterns in two countries with different welfare models: comparisons between Cuba and Denmark 1955–2020

“…Around the turn of the twenty-first century, mortality patterns in Cuba and Denmark were almost identical, although historical mortality experiences differed substantially. This historical difference may have affected the perception of survival expectations differently in the two populations, which may have influenced decision-making (Nepomuceno et al, 2021 ). However, our study was based on period life tables, precluding the advantages of preferable cohort life tables, which would have required complete and very long-term historical mortality series for both countries.…”

Evaluation of age-specific causes of death in the context of the Italian longevity transition

“…This positive trend has been accompanied with substantial reductions in lifespan inequality. This means that Italians are not only living longer but also their lifespans have become more predictable, which can have implications for life course decisions, such as when to invest in education or when to retire 7,12 . From a public health perspective, this finding reflects that improvements in mortality have become more egalitarian over the age span.…”

“…While life expectancy is an important indicator of longevity, it conceals variation in lifespans or lifespan inequality, which can be substantial 6 . Lifespan inequality matters because it reflects individuals' uncertainty in the timing of death, which can be important for life course decisions 7 , and it measures how uneven improvements in mortality are at the population level 8 . From a public health perspective, greater lifespan inequality implies increasing vulnerability at the societal level and the consequent ineffectiveness of policies to protect individuals against life course risks 9 .…”

Evaluation of age-specific causes of death in the context of the Italian longevity transition

“…This positive trend has been accompanied with substantial reductions in lifespan inequality. This means that Italians are not only living longer but also their lifespans have become more predictable, which can have implications for life course decisions, such as when to invest in education or when to retire 9 , 14 . From a public health perspective, this finding reflects that improvements in mortality have become more egalitarian over the age span.…”

“…While life expectancy is an important indicator of longevity, it conceals variation in lifespans or lifespan inequality, which can be substantial 8 . Lifespan inequality matters because it reflects individuals’ uncertainty in the timing of death, which can be important for life course decisions 9 , and it measures how uneven improvements in mortality are at the population level 10 . From a public health perspective, greater lifespan inequality implies increasing vulnerability at the societal level and the consequent ineffectiveness of policies to protect individuals against life course risks 11 .…”