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Smoking cessation for 30 years confers reduced PAD risk similar to never smokers
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Smoking has been shown to have significant associations with peripheral artery disease, CHD and stroke, with the strongest link seen for PAD, according to a study published in the Journal of the American College of Cardiology.
The study also found that the increased risk for PAD persisted for up to 30 years after smoking cessation and the risk for CHD continued for 20 years.
“It is important to recognize that the risk of the atherosclerotic diseases started to decline after smoking cessation in a short time frame of < 5 years, which would be encouraging to persons attempting or considering quitting smoking,” Ning Ding, MBBS, ScM, data analyst at Johns Hopkins Bloomberg School of Public Health, and colleagues wrote. “In addition, a clear dose-response relationship between the length of smoking cessation and lower risk of atherosclerotic diseases may encourage individuals with short-term smoking cessation to maintain cessation.”
ARIC study data
Researchers analyzed data from 13,355 participants (mean age, 54 years; 56% women) from the ARIC study aged 45 to 64 years without CHD, PAD and stroke at baseline. Information on smoking status, age smoking started and stopped, and smoking intensity was collected during a baseline interview.
Outcomes of interest included hospitalizations and deaths. Follow-up was conducted until death, a CV outcome, date of last contact or September 2015, whichever occurred first.
Of the participants in the study, 25% were current smokers, 31% were former smokers and 44% were never smokers. During a median follow-up of 26 years, there were 1,798 cases of CHD, 492 cases of PAD and 1,106 cases of stroke.
Participants who smoked for at least 40 pack-years had an estimated fourfold increased risk for PAD compared with those who never smoked. The HR for CHD was 2.1 and 1.8 for stroke. The link to pack-years was stronger for PAD compared with stroke and CHD (P for difference < .001). A stronger association with PAD vs. CHD and stroke was seen when smoking intensity and duration were assessed separately.
Compared with current smokers, participants who quit smoking for 5 to less than 10 years had an HR of 0.71 for CHD (95% CI, 0.57-0.88), 0.43 for PAD (95% CI, 0.28-0.64) and 0.61 for stroke (95% CI, 0.45-0.82). Smoking cessation for at least 30 years resulted in an HR of 0.47 for CHD (95% CI, 0.39-0.56), 0.22 for PAD (95% CI, 0.16-0.31) and 0.49 for stroke (95% CI, 0.39-0.62).
Participants who quit smoking for at least 30 years had a similar risk for PAD compared with those who never smoked. When participants quit smoking for 20 to less than 30 years, there was still an elevated HR for PAD (HR = 1.71; 95% CI, 1.2-2.44).
“Our study provides evidence for an anti-smoking campaign to continue to advocate smoking prevention and cessation,” Ding and colleagues wrote. “Although public statements about smoking and CVD have been focusing on CHD and stroke, our results indicate the need to take account of PAD as well for comprehensively acknowledging the effect of smoking on overall cardiovascular health.”
Understanding tobacco use
“Clinicians’ experience may be that smokers are not ready to quit, that treatments are ineffective or that long-term success is rare,” Nancy Rigotti, MD, professor of medicine at Harvard Medical School and director of the Tobacco Research and Treatment Center at Massachusetts General Hospital, and Mary M. McDermott, MD, Jeremiah Stamler Professor and professor of medicine (general internal medicine and geriatrics) and preventive medicine at Northwestern University Feinberg School of Medicine, wrote in a related editorial. “This stems from a misunderstanding of the nature of tobacco use. It is best understood as a chronic relapsing disorder driven by nicotine dependence whose treatment is characterized by repeated cycles of abstinence and relapse. Nonetheless, long-term tobacco abstinence is achievable using a chronic disease management approach resembling the strategies used to manage other risk factors.” – by Darlene Dobkowski
Disclosures: Ding reports no relevant financial disclosures. Rigotti reports she received royalties from UpToDate, consulted for Achieve Life Sciences and received travel expenses from Pfizer. McDermott reports she received research funding from Regeneron and received other research support from Chromadex, Hershey Company, ReserveAge and ViroMed. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Elizabeth Ratchford, MD
As I teach my fellows and students, I always tell them that 80% of people with PAD are current or former smokers, and that you’re twice as likely to develop PAD as you are to develop CHD if you smoke. However, the references for these statistics date back to the 1990s. It’s nice to have updated data that confirms, in fact, that you’re still twice as likely to develop PAD as you are to develop CHD if you smoke.
The current JACC study found that there is a fourfold increased risk for PAD if you smoke compared with never smokers if you smoke greater than 40 pack-years, and that corresponding HR was 2.1 for CHD. It’s great to have solid and legitimate information that’s up to date and accurate to confirm what we’ve always been saying.
It’s also good to see for the public that this increase in risk doesn’t ever really go away, at least not for 30 years. Clearly, the longer it has been since you quit, the lower your risk, but 30 years is a long time. It’s positive information for the patients to realize that there’s a direct relationship between how many years it has been since you quit smoking and your risk.
Meanwhile, it is important for us as clinicians to realize that if a patient has ever smoked, then we should really be on high alert for PAD. That supports what we see clinically — I’ll have patients who come in with claudication and newly diagnosed PAD and they ask, “Why did this happen to me?” I tell them, “As the arteries get older, they can clog up with plaque, but smoking is really the most important risk factor for PAD; diabetes is a close second.” They’ll then say, “I don’t have diabetes and I quit smoking 15 years ago.” As it shows in this study, that doesn’t matter. The changes occur in the blood vessels and the risk persists. We must keep in mind that a distant history of smoking is still a major risk factor, especially for PAD. We should be particularly aware in vulnerable populations based on this study.
For this group and for all our patients, we need to get them to quit smoking and ideally not to start smoking. To achieve that goal, clinicians may want to use the ACC decision pathway on tobacco cessation treatment that we recently published in JACC (Barua RS, et al. J Am Coll Cardiol. 2018;doi:10.1016/j.jacc.2018.10.027). Extensive thought and data analysis went into that document. It should be a good resource for clinicians to address some of the more controversial aspects of smoking cessation and how to approach electronic cigarettes. First-line pharmacologic therapy for smoking cessation should be varenicline (Chantix, Pfizer) or dual nicotine replacement therapy along with the behavioral intervention. Medication and behavioral support should go hand in hand.
Patients who smoke should be offered pharmacologic treatment every visit. The CV risk is so strong that cardiologists, CV specialists and vascular medicine specialists should take a proactive role in the actual prescription, not just writing, “May consider adding varenicline,” and sending the patient back to the primary care doctor. We need to step up and help because this is our area; we need to own it and we need to treat it.
We have a lot of great research (including the current study by Ding and colleagues) about the risks of smoking combustible cigarettes. Going forward, the biggest area of research is going to be the short- and long-term effects of e-cigarettes. That’s the problem for young people and the initiation of smoking. In this study, the large majority of people were younger than 20 years when they started smoking. Meanwhile, e-cigarettes were not even in existence when the ARIC study started.
As Scott Gottlieb, MD, former commissioner of the FDA, said, electronic cigarettes are truly the epidemic at this point.
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