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Study Finds Smoking Health Effects Linger Longer Than Previously Thought

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Smoking has long been tied to an increased risk of cardiovascular disease. But until now, the evidence has pointed to heavy smokers’ risk returning to normal five years after quitting. A new study released Tuesday from Vanderbilt University Medical Center found it takes much longer for heavy smokers’ bodies to recover: 10 to 15 years until the risk returns to the level of someone who has never smoked. Heavy smokers were defined as smoking the equivalent of a pack a day for 20 years. 

“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,” said Vanderbilt lead study author Meredith Duncan. 

There is a bright spot in the study though: cardiovascular risk does decline dramatically within five years after quitting, compared to people who keep smoking. 

“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 said. “And so that's a huge benefit.”

When a lot of people think about smoking, they don’t think about these heart risks - they think about cancer. And indeed, cigarette smoking is linked to about 80 to 90 percent of lung cancer deaths, according to the Centers for Disease Control and Prevention. 

Cancer is what Tim Dunn thought about initially. He was at the Kentucky State Fair looking at tobacco leaves on Saturday. 

“I mean, there's people who smoke every day of their life and don't get cancer — and then there's people who've never smoked and have cancer,” Dunn said. “So that's the way I look at it. It's kind of the luck-of-the-draw thing for me.”

Dunn said he isn’t a cigarette smoker, though he occasionally smokes cigars. But he also acknowledged that people who smoke are generally not as healthy as people who have never smoked. 

“Obviously, if you smoke, you're not gonna be in good health as a nonsmoker, but I guess at the same time, it's your decision,” Dunn said. 

But his opinions on smoking are also nuanced: he said he wouldn’t want his daughter to smoke. 

Shaping What Doctors Say

Duncan at Vanderbilt said doctors and other health providers should consider the study when treating patients. For instance, medical advice might change for a patient who quit seven years prior. 

“That falls within that time of like — well, the risk calculator said that by now that risk should have diminished — but these findings suggest that maybe they haven't,” Duncan said. “Physicians really want to err on the side of caution. They may want to say, ‘For up to 10 years, we're going to consider you to be at higher risk.’” 

In that case, a health provider might still advise changes to diet and exercise that could decrease risk.

The risk calculator is a tool health providers use to determine a patient’s likelihood of developing health conditions. Duncan said there needs to be more research before her study’s finding is conclusive. 

“It would be really premature to say that calculators should be updated based on these results alone,” Duncan said. 

The data she used is from the Framingham Heart Study, which started in 1954. That study followed a generation and gave participants a medical exam every few years. In addition, another generation of people was enrolled starting in the 1970s and also examined every few years. The 8,770 people in the dataset are predominantly white and live in a community outside Boston. And though it’s a huge data set, Duncan said that means the study has limitations. 

“We don't know that this extends to other races or ethnicities,” Duncan said. 

Next up for Duncan and her team is an experiment with the existing heart risk calculator. They’re using the current algorithm for the calculator, and adding in questions about the time since a person quit and how heavily they smoked. The hypothesis is that making 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. 

Lisa Gillespie is WFPL's Health and Innovation Reporter.

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