News of an income gap between the rich and poor in the United States would surprise very few, but a new study has documented another troubling divide in the country, this one in how long people can expect to stay alive. The study shows a 40-year difference between the longest-lived people in the nation--Asian American women in parts of New York, New Jersey, and Florida who live on average into their late 90s-and the shortest-lived--Native American men in six South Dakota counties who on average live only until their mid-50s.

"That's an absolutely staggering range," says the study's editor, Christopher J. L. Murray, professor of international health economics at the School. "Even if you took all of Europe, you would not find that variation."

The study is called the U.S. Burden of Disease and Injury study, which has the acronym-derived nickname of US BODI. The result of a massive research project spearheaded by Murray in conjunction with health statisticians at the Centers for Disease C ontrol and Prevention in Atlanta, the ultimate goal of US BODI is to comprehensively assess the impact of 200 different diseases and forms of injury on the United States populace. The full-dress version of the study won't be out until later this fall, but some preliminary results were released earlier this year, including the provocative county-by-county tabulation of life expectancy. US BODI is one of many national and regional spinoffs of Murray and Alan Lopez's massive Global Burden of Disease study pu blished in 1996. This study calculated the current causes and societal impact of premature death and disability throughout the world and made projections about what they will be over the next several decades.

The life expectancy part of US BODI relied on a review of death certificates from 1959 to 1994. The good news is that since the 1950s, average life expectancy for men and women across the country has risen steadily; women have done particularly well, gaining on average almost 10 years of life. White women in several counties scattered throughout Minnesota and North and South Dakota are nearly as robust as Asian American women, with average life expectancies of 83. The picture is not as rosy, however, for non-white groups. Black women are making slight gains in life expectancy, but the line charting the life expectancy for black men remains nearly horizontal across the three and a half decades. The figures for Native American men in those six South Dako ta counties are chilling: men in places like Bangladesh can look forward to living longer.

US BODI points to a correlation between the gap in life expectancy in this country and the huge gap in incomes between the nation's richest inhabitants and its poorest. This finding may be consistent with research done at the School and elsewhere demonstrating that as the separation of rich and poor gets wider, life expectancy for both groups goes down. At the same time, the study shows that poverty doesn't automatically lead to shorter life spans. For example, the parts of Texas that border Mexico rank as one of the nation's poorest regions, yet people living there have life expectancies above the national average. At the other end of the income scale, the urban East Coast area from Boston to Washington, D.C., includes some of the country's highest per capita income communities, but not the highest average life expectancies.

As interesting as it is, this life expectancy profile of the country is actually only the first slice of the data assembled by the US BODI researchers. The full study will include information on how factors such as educational level and income may play into premature death and disability. And like its parent Global Burden of Disease study, the US BODI project has been billed as a sharp departure from past efforts to assess health status at a macro level. In the past, health officials and researcher s taking stock of global or country-level health relied primarily on life expectancy and infant mortality statistics. Using a measurement called Disability Adjusted Life Years, or DALYS, the full US BODI project will go beyond those stark, beginning- and end-of-life numbers to put statistics on the gray area of all the disability in between. By using DALYS, researchers can track how much disability or premature death is caused by a particular disease, such as cancer, and compare these answers to the amount of disability or premature death caused by something from an entirely different realm, such as traffic or gun accidents.

Such comparisons are key for determining the cost effectiveness of prevention programs and other interventions, says Jim Marks, director of the National Center for Chronic Disease Prevention and Health Promotion at the CDC. Marks's Center is producing US BODI with Murray and his Harvard Burden of Disease Unit. Marks notes that Americans spend vast sums on medical procedures, such as surgery, to correct the debilitating effects of late-stage heart disease, for which the patients may only gain a few extra years of life. US BODI "will force us to come to grips with our values," says Marks. "We put a lot of effort into saving a few lives. We should do that recognizing the tradeoffs we make."

- Terri L. Rutter