Study finds it takes longer than previously thought for a heavy smokers’ risk of heart disease to be the same as a non-smoker

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Quitting smoking has immediate benefits to the heart, but it takes longer than previously thought for a former smoker’s risk of heart disease to return to the level of someone who has never smoked, Lisa Gillespie reports for Louisville’s WFPL.

“The conventional wisdom is that within five years of smoking cessation, your cardiovascular risk goes back to that of someone who has never smoked, [but] we found that it could take longer,” lead study author Meredith Duncan, of the Vanderbilt University Medical Center, told Gillespie.

The study, published in the Journal of the American Medical Association, found that among heavy smokers, within five years after quitting, a person’s risk of heart disease is significantly lower than that of a person who continues to smoke, but it takes 10 to 15 years, and as much as 25 years, before their risk is the same as a person who has never smoked. A heavy smoker is someone who has smoked a pack a day for 20 years.

“Even among these really heavy smokers, we found that there’s a huge benefit of quitting, and that they experienced a 39 percent reduced risk of cardiovascular disease within five years of smoking cessation relative to people who continue to smoke,” Duncan told Gillespie.

“The upper estimate of this time course is a decade longer than that of the Nurses’ Health Study results for coronary heart disease and cardiovascular death and more than 20 years longer than in some prior reports for coronary heart disease and stroke,” says the study report.

Most concern about smoking is related to cancer, with little thought to how it affects the heart, Gillespie writes. She notes that cigarette smoking is linked to about 80% to 90% of lung cancer deaths, according to the Centers for Disease Control and Prevention, but smoking is a major risk factor for heart disease and is responsible for 20% of all deaths from heart disease, the study says.

Duncan told Gillespie that doctors and other health-care providers should consider the study when treating patients who have quit smoking.

“Physicians really want to err on the side of caution,” she said. “They may want to say, ‘For up to 10 years, we’re going to consider you to be at higher risk’.”

Data for the study came from the nearly 8,800 men and women who took part in the Framingham Heart Study, a long-term, ongoing study of factors that contribute to heart disease. Duncan cautioned that the Framingham study is predominantly made up of white people who live in a community outside Boston, so it is not certain if these findings extends to other races or ethnicities.

Duncan told Gillespie that she and her team will now experiment with the existing heart risk calculator, a tool that is used for those who have not had a prior heart event, to predict their risk of a heart attack or stroke. She said they are adding questions about the time since a person quit and how heavily they smoked.

The researchers’ hypothesis is that those additions might line up the risk calculations with her study results. “We want to see if … adding just those two variables to the calculator helps in aiding risk prediction among former smokers,” Duncan said.