Are estimates of 'potential gains in life expectancy' potentially unreliable?

Objectives: The objective of this study was to investigate whether estimates of 'potential gains in life expectancy' (PGLE) are potentially unreliable. Study design: We compare the sum of the PGLEs from actual 1999-2017 reductions in U.S. mortality from all causes to the actual change in life expectancy of the entire population. Methods: Multiple-decrement life table techniques are used to calculate the PGLEs from the actual reductions in age-specific rates of mortality from 113 causes. Then, the sum of the estimated PGLEs is compared to the actual change in life expectancy (LE) of the entire population. Results: The sum of the estimated gains in LE at birth is 40% larger than the actual increase in LE at birth: 2.7 years vs 1.9 years. The sum of the estimated gains in LE at age 65 years is 40% smaller than the actual increase in LE at age 65 years: 1.0 years vs 1.7 years. Conclusions: The fact that the sum of the estimated gains in LE from all diseases differs substantially (in both directions) from the actual increase in LE suggests that estimates of PGLE are potentially unreliable. (C) 2020 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.