Quitting smoking at any age quickly brings big health benefits: study

People who quit smoking see significant gains in life expectancy after just a few years, according to a new study led by University of Toronto researchers at Unity Health Toronto.

The study, published in NEJM proof, shows that smokers who quit before age 40 can expect to live almost as long as those who have never smoked. Those who quit at any age find survival close to that of non-smokers 10 years after quitting, and about half of these benefits occur in just three years.

“Quitting smoking is ridiculously effective in reducing the risk of death, and people can reap these rewards remarkably quickly,” said Prabhat Jha, a professor at the Dalla Lana School of Public Health and the Temerty Faculty of Medicine at the University of Toronto, and Executive Director of the Center for Global Health Research at Unity Health Toronto.

The observational study involved 1.5 million adults in four countries (US, UK, Canada and Norway), followed for 15 years. Smokers aged 40 to 79 were almost three times more likely to die than those who had never smoked, meaning they lost an average of 12 to 13 years of life.

Former smokers reduced their risk of death to 1.3 times (or 30% more) than former smokers. Quitting smoking at any age was associated with longer survival, and even those who quit smoking for less than three years gained up to six years of life expectancy.

“Many people think it’s too late to quit smoking, especially in middle age,” Jha said. “But these results run counter to that idea. It’s never too late, the impact is rapid, and you can reduce the risk of major diseases, which means a longer, better life.”

Researchers found that quitting smoking reduced the risk of dying from vascular diseases and cancer, in particular. Former smokers also reduced their risk of death from respiratory disease, but to a lesser extent, likely due to residual lung damage.

There are currently around 60 million smokers in the four countries covered by the study, and more than a billion worldwide. Global smoking rates have declined by more than 25 percent since 1990, but tobacco remains a leading cause of preventable death.

Jha said the findings should add urgency to governments’ efforts to support people who want to quit smoking. “Helping smokers to quit is one of the most effective ways to significantly improve health. And we know how to do it, by increasing taxes on cigarettes and improving quit measures tobacco.”

Canada has long overdue an increase in the federal excise tax on cigarettes, and many other countries could reduce smoking rates by raising taxes, Jha said. Supports for quitting may include clinical guidelines and patient resources such as helplines, but also a whole health system approach.

“When smokers interact with the health care system in any way, doctors and health professionals can encourage them to quit, emphasizing how quitting smoking works,” Jha said. “This can be done with concern, without judgment or stigma, recognizing that cigarettes are designed to be highly addictive.”