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Review
. 2020;66(1):95-104.
doi: 10.1159/000500955. Epub 2019 Aug 7.

Life Expectancy: Frequently Used, but Hardly Understood

Marc Luy  1   2 , Paola Di Giulio  3   4 , Vanessa Di Lego  3   4 , Patrick Lazarevič  3   4 , Markus Sauerberg  3   4
Affiliations
Review

Life Expectancy: Frequently Used, but Hardly Understood

Marc Luy et al. Gerontology. 2020.

Abstract

Period life expectancy is one of the most used summary indicators for the overall health of a population. Its levels and trends direct health policies, and researchers try to identify the determining risk factors to assess and forecast future developments. The use of period life expectancy is often based on the assumption that it directly reflects the mortality conditions of a certain year. Accordingly, the explanation for changes in life expectancy are typically sought in factors that have an immediate impact on current mortality conditions. It is frequently overlooked, however, that this indicator can also be affected by at least three kinds of effects, in particular in the situation of short-term fluctuations: cohort effects, heterogeneity effects, and tempo effects. We demonstrate their possible impact with the example of the almost Europe-wide decrease in life expectancy in 2015, which caused a series of reports about an upsurge of a health crisis, and we show that the consideration of these effects can lead to different conclusions. Therefore, we want to raise an awareness concerning the sensitivity of life expectancy to sudden changes and the menaces a misled interpretation of this indicator can cause.

Keywords: Cohort effects; Harvesting effect; Heterogeneity; Life expectancy; Tempo effects.

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Figures

Fig. 1
Fig. 1
Trends in period life expectancy (PLE, left y axes) and the total mortality rate (TMR, right y axes) in selected countries, women, 2009–2015. a Belgium. b France. c The Netherlands. d UK.
Fig. 2
Fig. 2
Changes in period life expectancy (PLE), tempo-adjusted life expectancy (LE*), cross-sectional average length of life (CAL), and mean age at death (MAD) relative to 2009 in selected countries, women, 2009–2015. a Belgium. b France. c The Netherlands. d UK.
See this image and copyright information in PMC

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