TUESDAY, Jan. 7, 2014 (HealthDay News) -- Efforts to limit tobacco use over the past 50 years have prevented 8 million premature deaths in the United States, giving those people an average of nearly 20 additional years of life, according to a new study.
The 1964 U.S. Surgeon General's report on the ills of smoking launched a great public health success story, said the authors of the study, which was published in the Jan. 8 issue of the Journal of the American Medical Association.
By calculating the number of people who have avoided premature death by not smoking, the researchers found that, because fewer people light up, overall life expectancy at age 40 has increased by about two years.
The study's results reveal the power of smoking prevention, said study co-author Rafael Meza, an assistant professor of epidemiology at the University of Michigan School of Public Health.
However, 18 million Americans died during the study period. "That's still a huge toll," Meza said. "Only about a third of potential deaths have been prevented."
The findings are estimates, since there's no way to know for sure how many people would have smoked if the health risks of smoking weren't made clear, Meza said.
Dr. Mark Pletcher, an associate professor of epidemiology and biostatistics at the University of California, San Francisco, praised the study. "[It's] an important demonstration of the power and benefits of prevention," Pletcher said.
The researchers launched the study to gain more understanding of how efforts to control tobacco in the United States affected death tolls. In 1964, almost 60 percent of men and more than one-third of women smoked, Meza said. Today, less than 20 percent of adults smoke.
After the Surgeon General's report came out in 1964, smoking began to decline amid restrictions on tobacco advertising, regulations that limited where people could smoke and greater awareness of risks. Cigarette packs warned that smoking could be hazardous to health, and the government levied higher taxes on tobacco, making it more expensive to light up.
How did the researchers arrive at their estimates? They figured that without the alarms over smoking the percentage of smokers would have stayed fairly stable or declined among men and grown or stayed fairly stable among women from 1964 to 2012. Then they determined what these changes would have meant for the rates of death from smoking and compared them to actual figures.
The researchers estimated that tobacco-control efforts prevented 5.3 million deaths among U.S. men and 2.7 million deaths among women between 1964 and 2012. During that time, life expectancy at age 40 grew by 7.8 years for men and 5.4 years for women. According to the researchers' calculations, curbs on smoking accounted for 2.3 of those additional years for men and 1.6 years for women.
Smoking still claims hundreds of thousands of lives a year in the United States, the researchers said.
In the future, Pletcher said, researchers need to determine which strategies are most effective at reducing smoking. They'll also need to think about when enough is enough, he said. "At some point, there's got to be an issue of diminishing returns," he said.
"There will be some smokers out there who will never quit, and it's not worth spending our public health dollars banging our head against the wall," he said. "We'll need to think about how to prioritize public health spending."
For more about smoking, see the U.S. National Library of Medicine.