TORONTO - Women who smoke have a dramatically higher risk of developing an abdominal aortic aneurysm than those who never used tobacco, say researchers, adding yet another reason to the long list of reasons for butting out or avoiding getting hooked in the first place.
In a study published online Tuesday by the British Medical Journal, researchers found that female smokers are four times more likely to have an aortic aneurysm rupture or need repair, compared to women who have quit smoking.
Furthermore, women who smoke have an eight-fold higher risk of rupture or the need for repair than those who never took up the habit, the study found. Previous research has shown that tobacco use amplifies the prevalence of aortic aneurysms in men, as well.
"Smoking is much more potent a factor on aortic aneurysm than it is in coronary artery disease or cerebral vascular disease ... many times more," said lead author Dr. Frank Lederle, referring to the increased risk of heart attack and stroke due to smoking's contribution to diseased blood vessels.
"What we don't know is the method of causation," Lederle, an internist at Minnesota's VA Medical Center, said Tuesday from Minneapolis.
An aneurysm occurs when an area in the wall of the aorta -- the body's largest artery that runs from the heart to the abdomen before dividing into two blood vessels to the legs -- is weakened and begins ballooning out. The aneurysm can rupture, causing a person to bleed to death within seconds to hours.
Although more common in men, abdominal aortic aneurysms are more deadly in women. Proportionally fewer women than men survive surgery to repair the artery.
But the condition is often under the radar for both doctors and patients.
"There are no symptoms until the aneurysm begins to rupture," Lederle said. "And that can be 10 years after it starts to form. So here's a disease that lies dormant for many years, easily detectable with ultrasound and yet frequently isn't detected and ultimately can be disastrous, because once rupture begins, 75 to 80 per cent of people who start to rupture will die."
"Half never get to an operating room and the operative mortality is over 50 per cent."
The research involved analyzing data from the U.S. Women's Health Initiative study, and looked at risk factors for rupture and repair of abdominal aortic aneurysms in almost 162,000 postmenopausal women, who were followed for an average of about eight years.
There were 184 reported aneurysm repairs or ruptures during the study and 14 deaths were directly attributed to the condition.
Intriguingly, the researchers found that women on hormone replacement therapy or with diabetes had a lower risk of aneurysm events occurring.
Previous studies have shown that diabetic men are also less likely to develop abdominal aortic aneurysm.
As for the effects of HRT, more research will be needed to determine the role of the therapy in preventing the condition in women. However, Lederle speculated that female hormones like estrogen and progesterone are thought to help keep blood vessels healthy.
"We're certainly not advising anyone to take hormone replacement therapy for this purpose, because we have large randomized trials in the Women's Health Initiative that show it's not beneficial across the full range of important (health) effects," he said.
"What we're saying is that, curiously, it seems in this study to be protective of this one disease, and so that should guide future laboratory research, maybe drug development, but absolutely should not be a recommendation to treat with hormone replacement therapy to prevent aortic aneurysm."
In an accompanying BMJ editorial, Prof. Janet Powell of Imperial College London and Prof. Paul Norman of the University of Western Australia said that the findings emphasize the need for educating women about quitting smoking to remain a public health priority.
They warn that if the incidence of abdominal aortic aneurysm in women continues to rise, then a population screening program for women who have smoked or continue to smoke may need to be implemented.
Last month, the Canadian Society for Vascular Surgery called for a national ultrasound screening program for abdominal aortic aneurysms in all men aged 65 to 75 and high-risk women 65 and older. The condition occurs in about five per cent of men and almost one per cent of women over 65.
