Smokers have 6- to 7-fold increased risk of AAA than people who never smoked

More than 10 percent of current smokers and more than 5 percent of adults developed an abdominal aortic aneurysm (AAA) during a median follow-up period of 22.5 years, according to a community-based, prospective study.

Current smokers had a 6- to 7-fold higher risk of clinical AAA and ultrasound-detected asymptomatic AAA compared with people who never smoked.

The trial also found that adults who quit smoking for at least 3 to 8 years before the follow-up period began had a 29 percent lower lifetime risk of AAA compared with continuous smokers. However, those adults who recently quit smoking had a 2.6 to 3.5 fold increased risk of AAA in the next 15 years compared to people who never smoked.

Lead researcher Weihong Tang, PhD, MS, MD, of the University of Minnesota, and colleagues published their results online in Arteriosclerosis, Thrombosis and Vascular Biology on Nov. 10. The National Heart, Lung, and Blood Institute helped fund the trial.

“Our study quantified the lifetime risk of an abdominal aortic aneurysm and found that it was far from trivial for smokers,” Tang said in a news release. “And we quantified the benefit of quitting smoking, which turns out to be substantial.”

The researchers evaluated 15,792 adults who participated in the ARIC (Atherosclerosis Risk in Communities) study and were at risk of developing AAA. The mean age at baseline was 54.2 years old, while 44.8 percent of participants were males, 26.1 percent were current smokers and 41.7 percent never smoked.

The researchers identified 590 clinical AAA events from the first visit (between 1987 and 1989) through 2011. The crude incidence rate of AAA was 1.90 per 1,000 person-years. They also identified 75 additional asymptomatic AAAs among the 5,778 participants who had an ultrasound examination in 2011 to 2013.

The lifetime risk of AAA was 5.6 percent in the overall cohort, including 8.2 percent in men, 6.5 percent in whites, 10.5 percent in current smokers and 11.1 percent in the top tertile of smoking pack-years.

After adjusting for several factors, the researchers found that smoking, white race, male sex, greater height and greater low-density lipoprotein or total cholesterol were associated with an increased risk of clinical AAA and asymptomatic AAA.

The researchers mentioned that the lifetime risk of AAA was lower than the risk of coronary heart disease, stroke and other cardiovascular diseases. However, the lifetime risk of AAA in high-risk subgroups was similar to that of breast cancer, venous thromboembolism and other chronic diseases.

The study had a few limitations, according to the researchers, including that it estimated the lifetime risk of AAA as the cumulative incidence through 85 years old, which could lead to underestimation of the risk.