Revisiting Mortality Deceleration Patterns in a Gamma-Gompertz-Makeham Framework

Abstract

We calculate life-table aging rates (LARs) for overall mortality by estimating a gamma-Gompertz-Makeham (ΓGM) model and taking advantage of LAR’s parametric representation by Vaupel and Zhang (Demogr Res 23(26), 737–748, 2010). For selected HMD countries, we study how the evolution of estimated LAR patterns could explain observed (1) longevity dynamics, and (2) mortality improvement or deterioration at different ages. Surprisingly, the age of mortality deceleration x∗ showed almost no correlation with a number of longevity measures apart from e0. In addition, as mortality concentrates at older ages with time, its characteristic bell-shaped pattern becomes more pronounced. Moreover, in a ΓGM framework, we identify the impact of senescent mortality on shape of the rate of population aging. We also find evidence for a strong relationship between x∗ and the statistically significant curvilinear changes in the evolution of e0 over time. Finally, model-based LARs appear to be consistent with point (b) of the “heterogeneity hypothesis” (Horiuchi and Wilmoth, J Gerontol Biol Sci 52A(1), B67–B77, 1997): mortality deceleration, due to selection effects, should shift to older ages as the level of total adult mortality declines.