Equity and length of lifespan are not the same

PNAS – Proceedings of the National Academy of Sciences of the United States of America
http://www.pnas.org/content/early/
(Accessed 16 July 2016)

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Social Sciences – Social Sciences – Biological Sciences – Medical Sciences:
Equity and length of lifespan are not the same
Benjamin Seligman, Gabi Greenberg, and Shripad Tuljapurkar
PNAS 2016 ; published ahead of print July 11, 2016, doi:10.1073/pnas.1601112113
Significance
We find that the causes of death that have led to greater equality among lifespans are different from the causes that have led to longer average lifespan, also called life expectancy. Control of leading causes of death, such as heart disease, increased life expectancy, whereas medical interventions on infant mortality led to greater equality. Action to promote health equity will require further mitigation of the killers of young people rather than solely focusing on the most common causes of death.
Abstract
Efforts to understand the dramatic declines in mortality over the past century have focused on life expectancy. However, understanding changes in disparity in age of death is important to understanding mechanisms of mortality improvement and devising policy to promote health equity. We derive a novel decomposition of variance in age of death, a measure of inequality, and apply it to cause-specific contributions to the change in variance among the G7 countries (Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States) from 1950 to 2010. We find that the causes of death that contributed most to declines in the variance are different from those that contributed most to increase in life expectancy; in particular, they affect mortality at younger ages. We also find that, for two leading causes of death [cancers and cardiovascular disease (CVD)], there are no consistent relationships between changes in life expectancy and variance either within countries over time or between countries. These results show that promoting health at younger ages is critical for health equity and that policies to control cancer and CVD may have differing implications for equity.