Cigarette smoking increases the risk of peripheral artery disease -- a common circulatory problem which reduces blood flow to limbs, and this elevated risk can persist up to 30 years after quitting, according to a study. The reduction of blood flow leads to limb pain, poor wound healing, and other signs and symptoms, said researchers at the Johns Hopkins Bloomberg School of Public Health in the US.
They also found that the link between smoking and peripheral artery disease was even stronger than that for coronary heart disease and stroke. The study, published in the Journal of the American College of Cardiology, found that compared with never-smokers, those who smoked for more than 40 pack-years had roughly four times more risk for peripheral artery disease, versus 2.1 times and 1.8 times more risk for coronary heart disease and stroke, respectively.
A pack-year is a parameter of smoking: 10 pack-years can mean one pack per day for 10 years or two packs per day for five years or some other combination. Similarly, participants who reported currently smoking more than a pack per day had a relative increased risk - 5.4 times more for peripheral artery disease versus 2.4 for coronary heart disease and 1.9 for stroke -- compared to those who had never smoked, researchers said.
The study is the first comprehensive comparison, in a large population moving through time, of the smoking-elevated risks of peripheral artery disease, coronary heart disease, and stroke.
The analysis was based on a sample of 13,355 participants, including 3,323 current smokers and 4,185 former smokers, who were tracked for a median period of 26 years.
Peripheral artery disease features the atherosclerotic buildup of cholesterol-laden deposits in arteries serving the legs. "Our results underscore the importance of both smoking prevention for nonsmokers and early smoking cessation for smokers," said Kunihiro Matsushita, an associate professor at the Bloomberg School.
"The study also suggests that campaigns about smoking's health risks should emphasise the elevated risk of peripheral artery disease, not just coronary heart disease and stroke," Matsushita said.
The effect of smoking on peripheral artery disease risk was not just stronger; it was also longer-lasting. Only after 30 years of smoking cessation did the peripheral artery disease risk for former smokers return to the baseline level seen in never-smokers.
By comparison, coronary heart disease risk took about 20 years to return to baseline after smoking cessation. Quitting smoking appeared to bring a meaningful drop in peripheral artery disease risk fairly quickly, researchers said.
"We observed a lower risk for peripheral artery disease, coronary heart disease, and stroke within five years of smoking cessation," said Ning Ding, a data analyst at the Bloomberg School.
Smoking cessation for five to nine years was linked to a much greater drop in peripheral artery disease risk, 57 per cent, compared to 30-40 per cent for coronary heart disease and stroke.