Most of the retreat in life expectancy came from increases in deaths from heart disease, chronic lower respiratory diseases, unintentional injuries, stroke, Alzheimer's disease, diabetes, kidney disease, and suicide, according to the CDC. Those causes, along with cancer, influenza and pneumonia, are the leading causes for death in the U.S., responsible for about three out of every four fatalities.
The total number of fatal drug overdoses increased by 11 percent last year to a record of 52,404, fueled by what is an epidemic of opioid use, both of prescription painkillers and heroin.
Fatal ODs's surpassed the number of car crash fatalities, which increased 12 percent to nearly 38,000. Deaths from car crashes, which had been declining for four decades, in 2015 saw the biggest increase in 50 years.
Deaths from gunshot, self-inflicted or otherwise, were close behind car-related deaths, increasing 7 percent to more than 36,000.
The increase in the U.S. death rate is "a big deal," Philip Morgan, a demographer at the University of North Carolina, told NPR. "There's not a better indicator of well-being than life expectancy ... The fact that it's leveling off in the U.S. is a striking finding."
When broken down by racial groups, age-adjusted death rates increased in non-Hispanic white males and females by the highest amounts, by 1 percent and 1.6 percent, respectively, in 2015. And They also increased 0.9 percent fr non-Hispanic black males.
But "rates did not change significantly for non-Hispanic black females, Hispanic males, and Hispanic females from 2014 to 2015," the CDC said.
Last year, after two Princeton economists drew widespread attention with a study featured in The New York Times that found that the death rate among middle-age whites since 1999 was rising in the United States — in contrast to all other racial and ethnic groupings in America, and unlike middle-age whites in other wealthy nations.
That study found that deaths from suicide, as well as from drugs and alcohol, were responsible for the trend since 1999. A follow-up story in the Times said younger white adults also had seen an increase in mortality rates, which was attributed primarily to increased abuse of prescription opioid painkillers.
But research released afterward by the Commonwealth Fund found that the increase in mortality among among middle-age, white Americans has more to do with "a lack of progress" in treating common illnesses than with the issues of substance abuse and suicide.
The Commonwealth Fund study said there had been a stall, and in some cases a reversal, of progress in reducing deaths among middle-age whites from common killers such as heart disease, diabetes and respiratory illness.
The study also found that the "worst trends" in mortality rates among white middle-age people are being seen in a group of seven mostly Southern states, including West Virginia, where white people between the ages of 45 and 54 are dying at the highest rates seen since 1980.