Income inequality takes eventual toll.

• Position: YOUR LIFE

Higher levels of income inequality in the U.S. lead to more deaths in the country over a period of years, claims a study published in Social Science and Medicine.

The findings suggest that income inequality at any one point does not work instantaneously--it begins increasing mortality rates five years later, and its influence peaks after seven years, before fading after 12 years.

"This finding is striking and it supports the argument that income inequality is a public health concern," asserts sociologist Hui Zheng, author of the study.

Many other studies have examined the impact of income inequality on mortality and have come up with mixed results, but Zheng thinks that this study overcomes problems in previous research by using a different data structure and statistical model (called a discreet-time hazard model). 'Current mortality isn't just affected by income inequality at one time, say 10 years ago. It is also affected by income inequality nine years ago, and 11 years ago, and the current level of inequality, and so on."

In this study, Zheng was able to look at deaths in a particular year and control for income inequality for each of up to 21 years preceding the death.

"For the first time, we can clearly capture the long-term effect of income inequality on health. Previous studies are likely to miss the effect if the mortality follow-up period is too short for income inequality to...