NEW YORK — A decades-long trend of rising life expectancy in the U.S. could be ending: It declined last year and it is no better than it was four years ago.
In most of the years since World War II, life expectancy in the U.S. has inched up, thanks to medical advances, public health campaigns and better nutrition and education.
But last year it slipped, an exceedingly rare event in a year that did not include a major disease outbreak. Other one-year declines occurred in 1993, when the nation was in the throes of the AIDS epidemic, and 1980, the result of an especially nasty flu season.
In 2015, rates for 8 of the 10 leading causes of death rose. Even more troubling to health experts: The U.S. seems to be settling into a trend of no improvement at all, and other Western nations are not seeing similar rises in mortality.
“With four years, you’re starting to see some indication of something a little more ominous,” said S. Jay Olshansky, a University of Illinois-Chicago public health researcher.
Still, experts cautioned against interpreting too much from a single year of data; the numbers could reverse themselves next year, they said.
“This is unusual, and we don’t know what happened,” said Jiaquan Xu, an epidemiologist and lead author of the study. “So many leading causes of death increased.”
An American born in 2015 is expected to live 78 years and 9½ months, on average, according to preliminary data released Thursday by the Centers for Disease Control and Prevention. An American born in 2014 could expect to live about a month longer, and even an American born in 2012 would have been expected to live slightly longer. In 1950, life expectancy was just over 68 years.
The U.S. ranks below dozens of other high-income countries in life expectancy, according to the World Bank. It is highest in Japan, at nearly 84 years.
The CDC report is based mainly on 2015 death certificates. There were more than 2.7 million deaths, or about 86,000 more than the previous year. The increase in raw numbers partly reflects the nation’s growing and aging population.
It was led by an unusual upturn in the death rate from the nation’s leading killer, heart disease. Death rates also increased for chronic lower lung disease, accidental injuries, stroke, Alzheimer’s disease, diabetes, kidney disease and suicide.
The only clear drop was in cancer, the nation’s No. 2 killer.
Experts aren’t sure what’s behind the stall. Some, like Mr. Olshansky, suspect obesity, an underlying factor in some of the largest causes of death, particularly heart disease.
Life expectancy at age 65 did not fall, another indication that the diseases behind the lower life expectancy occur in middle age or younger.
But there’s also the impact of rising drug overdoses and suicides, he noted. Drug overdose deaths soared 11 percent to more than 52,000 last year, the most ever, driven by increases in deaths from heroin, prescription painkillers and other so-called opioids. In fact, in a grim milestone, more people died from heroin-related causes than from gun homicides in 2015. As recently as 2007, gun homicides outnumbered heroin deaths by more than 5 to 1.
Average life expectancy declined for men, falling by more than two months, to 76 years and 3½ months in 2015. It fell by about one month for women, to 81 years and 2½ months, the CDC said.
Death rates increased for black men, white men, white women, and slightly for Hispanic men and women. But they did not change for black women.
The new CDC report did not offer a geographic breakdown of 2015 deaths, or analysis of death based on education or income. But other research has shown death rates are rising sharply for poorer people — particularly white people — in rural areas but not wealthier and more highly educated and people on the coasts. Indeed, the CDC last month reported that needle-sharing by white opiate addicts living in predominantly rural areas of the country are increasingly becoming vulnerable to HIV infections.
First Published: December 8, 2016, 2:25 p.m.
Updated: December 9, 2016, 4:55 a.m.