Cigarette smoking is a greater risk factor for peripheral artery disease (PAD) than for coronary heart disease (CHD) and stroke, and that risk persists far longer than for the other atherosclerotic diseases after smoking cessation, researchers reported.
Current smokers in the prospective cohort study with a ≥35 pack-year cigarette history had more than double the adjusted risk for developing PAD compared with the other two diseases (adjusted hazard ratios of 5.56, 2.30, and 1.91 for PAD, CHD, and stroke, respectively), according to Kunihiro Matsushita, MD, PhD, of Johns Hopkins Bloomberg School of Public Health in Baltimore, and colleagues.
The analysis of data on more than 13,000 participants, with a median of 26 years of follow-up, in the Atherosclerosis Risk in Communities (ARIC) study is among the first to show the long-term impact of cigarette smoking and smoking cessation on each of the three major atherosclerotic diseases, they wrote in the Journal of the American College of Cardiology.
Quitting smoking was associated with the greatest reduction in risk for PAD, with an 80% lower risk seen ≥30 following cessation.
But smoking-related risk also remained elevated following cessation for a longer period — roughly 3 decades versus 2 decades following cessation for CHD and 5 to 20 years for stroke, the authors reported.
Matsushita told MedPage Today that while the very strong association between smoking and PAD has long been recognized within the field of atherosclerotic medicine, it is not as well recognized outside the field.
“To my knowledge, this is the first study to prospectively quantify this risk in a single study population,” he said. “Policy statements addressing smoking have mainly focused on the risk of coronary heart disease and stroke. The recognition that the impact of smoking is largest for peripheral artery disease should definitely be part of the conversation moving forward.”
Matsushita added that younger smokers need to be made aware that their risk for PAD and the other atherosclerotic diseases can remain elevated for decades after they give up cigarettes.
“The impact of smoking on major artery disease may last up to 30 years,” he said.
In an accompanying editorial, Nancy Rigotti, MD of Massachusetts General Hospital/Harvard Medical School in Boston, and Mary McDermott, MD, of Northwestern University Feinberg School of Medicine in Chicago, stated that “Overall, [the findings] reinforce the existing public health message for smokers: it is never too early or too late to benefit from quitting.”
“It is never too late because of the relatively rapid reversal of cardiovascular disease risk after smoking cessation and never too early because complete risk reversal requires decades — even longer for PAD than for myocardial infarction or stroke, as this report demonstrates,” they wrote.
The study included 13,355 ARIC participants without PAD, CHD, or stroke at enrollment (from 1987 to 1989). Researchers evaluated the associations of pack years of smoking, duration of smoking, smoking intensity, and smoking cessation with incident PAD, contrasted with CHD and stroke via Cox modelling.
During a median follow-up of 26 years, a total of 492 PAD cases, 1,798 CHD cases, and 1,106 stroke cases were identified and a dose-response relationship was seen between pack-years of smoking and the three atherosclerotic diseases.
The authors reported that compared with never-smokers, people who smoked for ≥40 pack-years had approximately four-fold increased risk for PAD, 2.1-fold increased risk for CHD, and 1.8-fold increased risk for stroke.
Current smokers with ≥35 years of smoking duration showed hazard ratios of 5.56 (95% CI 4.26-7.26) for PAD, 2.30 (95% CI 1.98-2.66) for CHD, and 1.91 (95% CI 1.57-2.31) for stroke compared with never smokers.
Current smokers of ≥1 pack/day (higher intensity) had HRs of 5.36 (95% CI 4.1-6.91) for PAD, 2.38 (95% CI 2.08-2.73) for CHD, and 1.88 (95% CI 1.57-2.26) for stroke.
“There is a perception that (atherosclerotic) leg disease is less serious than heart or brain disease, but several recent studies have shown the prognostic impact of peripheral artery disease to be similar to CHD and stroke in terms of mortality and quality of life,” Matsushita told MedPage Today.
Study limitations included the self-reporting to smoking status, and the possibility that mild PAD cases were missed because the ascertainment of PAD was based on hospitalization with PAD diagnosis or leg revascularization, according to the authors.
The ARIC study was funded by the National Heart, Lung, and Blood Institute (NHLBI) and the Department of Health and Human Services.
Matsushita disclosed support from the NHLBI and relevant relationships with Fukuda Denshi.
Rigotti disclosed relevant relationships with Achieve Life Sciences and Pfizer. McDermott disclosed relevant relationships with Regeneron, the NHLBI, the National Institute on Aging, the American Heart Association, ChromaDex, Reserveage, Hershey, and ViroMed.