Health Risks Associated with Smoking Can Linger 30 Years After Quitting

A recent study is shedding new light on the long-term risks associated with smoking, which investigators discovered can linger for up to 3 decades. 





Investigators from the Johns Hopkins Bloomberg School of Public Health performed an analysis that included more than 13,000 patients and found, even after cessation, cigarette smoking boosts a person’s risk of peripheral artery disease for up to 30 years after cessation.

“Our results underscore the importance of both smoking prevention for nonsmokers and early smoking cessation for smokers,” said Kunihiro Matsushita, MD, PhD, study investigator and associate professor in the Department of Epidemiology at the Bloomberg School. “The study also suggests that campaigns about smoking’s health risks should emphasize the elevated risk of peripheral artery disease, not just coronary heart disease and stroke.”

To further evaluate long-term associations of cigarette smoking and its cessation with the incidence of coronary heart disease (CHD), peripheral artery disease (PAD), and stroke investigators performed an analysis using a sample of 13,355 patients within the Atherosclerosis Risk in Communities (ARIC) cohort. Investigators noted a desire to carry out a more comprehensive study than those previously done examining the issue — citing flaws within those studies including a lack of key smoking measures such as pack-years and duration.

A population of 15,792 were enrolled within the ARIC study, but investigators excluded patients whose race was recorded as other than white or black, had prevalent PAD at baseline, had prevalent CHD or stroke at baseline, or who had missing variables of interest from the present analysis. Baseline data on patients included smoking status, age smoking started, age smoking stopped, duration, and intensity.

At the baseline visit, patients were asked to specify how many cigarettes per day they smoked and investigators used this to quantify packs per day, which was used as their measure for smoking intensity. Packs per day was used to quantify pack-years, which was used as the measure for smoking duration.

Self-reported age, sex, race, educational level, and alcohol use were used as covariates. Additionally, BMI and several measurements including systolic and diastolic blood pressure and cholesterol levels were also included as covariates in the analysis. 



Of the 13,355 patients, 3323 (25%) identified as current smokers, 4185 (31%) as former smokers, and 5847 (44%) as never smokers. During a median follow-up of 26 years, investigators noted 492 PAD cases, 1794 CHD cases, and 1106 stroke cases. 



Upon analysis, investigators found that pack-years showed a graded-association with PAD after adjusting for confounders. Compared to never smokers, current smokers had a 5.4 times increased risk of PAD, a 2.4 times increased risk of CHD, and a 1.9 times increased risk of stroke. Investigators noted a significant trend between younger initiation and higher risk for CHD and a borderline trend for stroke.

Additionally, when compared with those who never smoked, only cessation for 30 or more years had a similar risk for PAD as never smoking and smoking cessation for 20 to 30 years was still found to be associated with an elevated risk (1.71; 95% CI, 1.20 to 2.44). In regard to CHD, the risk returned to baseline after about 20 years of smoking cessation.

In an editorial commentary, Nancy Rigotti, MD, of Massachusetts General Hospital, and Mary McDermott, MD, of the Feinberg School of Medicine, wrote the current study underscores the ever-present need to inform smokers of the immediate and long-term risks associated with smoking.

“They reinforce the existing public health message for smokers: it is never too early or too late to benefit from quitting,” wrote Rigotti and McDermott. “It is never too late because of the relatively rapid reversal of CVD risk after smoking cessation and never too early because complete risk reversal requires decades.”

This study, titled “Cigarette Smoking, Smoking Cessation, and Long-Term Risk of 3 Major Atherosclerotic Diseases,” is published in the Journal of the American College of Cardiology.