SAN ANTONIO—Current smokers who have a transient ischemic attack (TIA) are significantly younger than ex-smokers and nonsmokers who have a TIA, according to research presented at the 2010 International Stroke Conference. The finding suggests a potential role for smoking in inducing thrombus formation, reported Nandavar Shobha, DNB, DM.
“The age at presentation of current smokers with TIAs was significantly lower than in the other two groups, in spite of absence of significant neck vessel disease, suggesting a role of smoking-induced thrombus formation in even modest plaques,” said Dr. Shobha, who is a Stroke Fellow in the Calgary Stroke Program, Department of Clinical Neurosciences, University of Calgary. “This risk subsided with smoking cessation as evidenced by a later age at presentation of ex-smokers.”
Smoking, TIAs, and Strokes
Although smoking is a major modifiable risk factor for stroke, few studies have compared stroke incidence and age in smokers, ex-smokers, and nonsmokers, noted Dr. Shobha. She and her colleagues conducted a retrospective cohort study that compared the profile of ischemic strokes and TIAs among these three groups of patients.
A total of 1,047 subjects with TIA or acute ischemic stroke presented to the Foothills Medical Center in Calgary between April 2002 and May 2007. Each patient had undergone a CT of the head, as well as an angiogram of the head and neck. Demographic, clinical, and imaging details were obtained from a chart review. All participants were then grouped into three categories—current smokers, ex-smokers (those patients who had quit smoking for at least three months or longer), and nonsmokers.
The investigators defined TIA as a temporary neurologic dysfunction that lasted less than 24 hours, secondary to reduced blood supply of the brain and CT scan of the brain, showing no acute changes. An acute ischemic stroke was defined as a brain attack characterized by persistent neurologic deficits, with no evidence of hemorrhage on CT scan of the head.
Among the cohort, 233 participants (22.3%) were current smokers, 131 (12.5%) were ex-smokers, and 683 (65.2%) were nonsmokers. About 30% of both smokers and ex-smokers and 45% of nonsmokers were women.
Earlier TIAs Are Observed in Smokers
Dr. Shobha’s group found that the median age of stroke presentation among participants was 65.5 for current smokers, 68 for ex-smokers, and 67.6 for nonsmokers. “No significant difference [was observed] between the groups at age of stroke presentation,” she said.
The median age of TIA presentation was 56.7 for current smokers, 72.2 for ex-smokers, and 69.1 for nonsmokers. “Although the age at presentation of ex-smokers with TIA was higher compared to nonsmokers, the difference was not statistically significant,” Dr. Shobha noted. In addition, baseline scores on the NIH Stroke Scale ranged from 0 to 19 among those who had a TIA, and “there was no significant difference between the groups,” she said.
The researchers also found that ex-smokers had higher rates of hypertension and dyslipidemia than either current smokers or nonsmokers. Furthermore, “The incidence of anterior and posterior circulation strokes was not different in the three categories,” Dr. Shobha commented.
—Colby Stong