CVD risk may persist more than a decade after heavy smokers quit

Meredith Duncan

CHICAGO — CVD risk is reduced within 5 years after quitting smoking, but former smokers may remain at elevated CVD risk for up to 16 years compared with never smokers, according to data presented at the American Heart Association Scientific Sessions.

“All smokers experience a health benefit from quitting,” Meredith Duncan, MA, PhD student at Vanderbilt University Medical Center, told Cardiology Today. “We observed that, even among heavy former smokers with a lifetime exposure of 20 pack-years or more (one pack a day for 20 years), risk of cardiovascular disease decreased rapidly, with risk dropping by 38% within 5 years since quitting in heavy former smokers relative to continuing smokers. While risk is dramatically reduced within a few years, we also observed that it can take up to 16 years since quitting for former smokers’ cardiovascular disease risk to normalize to that of a never smoker.”

To examine CVD risk in former smokers, researchers used Framingham Heart Study data with two cohorts of 3,757 original participants (mean age, 50 years; 24 baseline pack-years) and 4,930 offspring participants (mean age, 36 years; 20 baseline pack-years) who did not have CVD when attending their fourth (between 1954 and 1958) or first (between 1971 and 1975) exams.

Researchers updated smoking and other variables every 2 years for the original participants and every 4 years for the offspring participants. Cohorts were analyzed both separately and together and CVD risk was compared in current, former and never smokers with adjustments for age, sex, education, exam decade, hypertension, diabetes, BMI, total cholesterol and alcohol consumption.

Participants were followed for incident CVD through 2014, equaling a median follow-up of 27 years. During this time, 2,386 CVD events occurred.

Researchers found that 71% of these events among ever smokers occurred in smokers who had greater than 20 pack-years.

Within 5 years of quitting, former smokers’ risk for CVD was reduced by 38%, but researchers also observed that the CI for the HR did not consistently include the null value of 1 until 16 years after quitting, suggesting that former smokers may remain at elevated CVD risk for more than 15 years after quitting when compared with never smokers.

“For patients who are current smokers, providers should continue encouraging these patients to quit,” Duncan said in an interview. “Former heavy smokers may remain at increased risk of cardiovascular disease for more than a decade after quitting, so we would encourage providers to continue to screen former smokers for development of CVD even in the absence of other risk factors.” – by Melissa J. Webb

Reference:

Duncan M, et al. Presentation Su1116. Presented at: American Heart Association Scientific Sessions; Nov. 10-12, 2018; Chicago.

Disclosures: The authors report no relevant financial disclosures.