A major study has found that mortality rates worldwide among adults under 60 have dropped over four decades by 34 percent for women and 19 for men but show a sharp increase in inequality across nations.
The new tally of adult mortality shows that a 15-year old girl in the country with the worst female death rate today, Zambia, is 16 times more likely to die before reaching the sixth decade of life than her counterpart in Cyprus, the nation on top of the ranking.
Of 1,000 young women in Zambia who are 15 today, in other words, less than 400 are predicted to reach the age of 60.
More broadly, the rates of mortality across all of southern Africa are, in 2010, higher than they were in Sweden in 1751, nearly two centuries before the widespread production of life-saving antibiotics, the study showed.
"With adult mortality, we are seeing this massive spread between the best and the worst off," said Christopher Murray, Director of the Institute for Health Metrics and Evaluation at the University of Washington in Seattle and the main architect of the study.
This stands in sharp contrast to the major progress since 1970 in both maternal mortality and children, he said in a statement.
Globally, the research confirms a reassuring downward trend in the rate of adult mortality over the period studied, 1970 to 2010.
But there were two regions that showed an alarming uptick in adult deaths in the 1990s, both for very different reasons, according to the study, published in the British journal The Lancet.
In much of sub-Saharan Africa, the backslide was most likely due to the HIV/AIDS epidemic, which has killed nearly 1.5 million people there annually in recent years.
During the same period, Eastern Europe saw one of the largest public health reversals of modern times after the collapse of the Soviet Union in 1991.
In the ranking of 187 nations, adult female mortality in Russia fell from 43rd in 1970 to 121 in 2010.
In Belarus, the drop over the same period was from 38th to 108th for women, and 81st to 150th for men, while Bulgaria plummeted from 14th and 12th in 1970 to 66th and 96th in 2010.
The study -- based on registration data, census data and records of household deaths rather than indirectly inferred from infant mortality, the method used up to now -- also shows that the risk of premature death has almost always been higher in men, sometimes twice as high.
The pattern emerging from each region is somewhat different.
In 1970, South Asia had the highest level of female mortality, but by 2010 it had declines by 56 percent.
Male mortality went down sharply over most of Asia, with Australia jumping from 44th to 6th place over the four decades under review.
The rankings of some wealthy nations for both men and women are less favourable in 2010 than they were in 1990, partly because of improvements in health elsewhere, but also due to an epidemic of "lifestyle" diseases related in particular to obesity.
The United States slipped from 34th and 41st place for men and women in 1990 to 49th and 45th respectively in 2010.
The five countries in 2010 with the lowest male adult mortality are, in order, Iceland, Sweden, Malta, the Netherlands and Switzerland.
For women, the countries are Cyprus, South Korea, Japan, Greece, Italy and Spain.
Over the four-decade period South Korea made spectacular gains, with its ranking for men rising from 167 to 31, and for women from 123 to 2.
Funding for the research came from the Bill and Melinda Gates Foundation.