Why did life expectancy decline in the United States in 2015? A gender-specific analysis.

In 2015, age-adjusted mortality rates increased for 8 of the 10 leading causes of death in the United States. As a result, life expectancy declined by 0.17 years for both women and men. The decline could be just an anomaly, or it could represent the start of a new trend of stagnation or decline in life expectancy, as some scholars have warned. The first step is to determine the sources of the decline. In this study we analyze the contribution of specific causes of death to the decline in men's versus women's life expectancy, as well as the mechanisms that generated the decline. With regard to mechanisms, we examine whether the decline in life expectancy resulted from reductions in the average age at death for most causes of death, or from a greater risk of dying of causes that disproportionately affect the young and middle-aged. Using CDC mortality data, we construct life tables for men and women separately, based on 20 different underlying causes of death. We find that men's reduction in life expectancy was attributable primarily to changes in midlife mortality, with a greater risk of dying of causes such as accidental poisoning or homicide. The reduction in women's life expectancy, on the other hand, was attributable primarily to changes in old-age mortality, where the mean age at death for most causes (such as heart disease and mental illnesses) was lower in 2015 than it was in 2014. These gender-specific mechanisms that contributed to the decline in life expectancy are common to the major racial/ethnic groups, but the magnitude of the decline differs greatly across racial/ethnic groups. Future research can use the tools provided here to investigate in more detail how the gender-specific mechanisms of the 2015 decline differ by race.