LOS ANGELES – The study on which the risk score is based was presented at the International Stroke Conference sponsored by the American Heart Association. Migraine with aura, for which younger women are at higher risk, increases the risk of ischemic stroke. “With our new risk-prediction tool, we could start identifying those at higher risk, treat their risk factors, and lower their risk of stroke,” said Souvik Sen, MD, MPH, professor and chair of neurology at the University of South Carolina in Columbia, in a press release.
Risk groups significantly discriminated stroke risk
To create the score, Dr. Sen and colleagues examined data from the(Atherosclerosis Risk in Communities) cohort, which includes community-dwelling people in Forsyth County, N.C.; Jackson, Miss.; Washington County, Md.; and the suburbs of Minneapolis. Researchers have been following the participants since 1987. From this population, Dr. Sen and colleagues identified 429 participants with a history of migraine with aura. Most of these participants were women aged 50-59 years at their first visit. The researchers analyzed the association between potential risk factors and ischemic stroke using Cox proportional hazards analysis.
Of the 429 participants, 31 had an ischemic stroke during a follow-up period of 20 years. Dr. Sen’s group created a risk score by identifying five risk factors for stroke and assigning them points in proportion to their influence (i.e., their regression coefficients). They assigned diabetes mellitus – 7 points; age older than 65 years – 5 points; heart rate variability (i.e., the standard deviation of all normal-to-normal RR intervals) – 3 points; hypertension – 3 points – and sex – 1 point. Then the researchers calculated risk scores for each patient and defined a low-risk group (from 0-4 points), a moderate-risk group (5-10 points), and a high-risk group (11-21 points).
After 18 years of follow-up, the incidence of stroke was 3% in the low-risk group, 8% in the moderate-risk group, and 34% in the high-risk group. The hazard ratio for ischemic stroke in the high-risk group, compared with the low-risk group, was 7.35. Kaplan Meier curves indicated that the risk-stratification groups significantly discriminated stroke risk among the sample. The risk score should be validated in an independent population cohort, said the investigators.
Dr. Sen and colleagues did not report any funding for this study. Investigators reported receiving grants from the National Institutes of Health, the American Heart Association, and the American Academy of Neurology.
Score may leave important variables unexamined
One mechanism through which migraine increases the risk of stroke is the constriction of blood vessels, said Louis R. Caplan, MD, professor of neurology at Harvard Medical School in Boston and member of the editorial advisory board of Neurology Reviews. Triptans, which many patients use to treat migraine, also cause vasoconstriction. In addition, migraine increases blood coagulation.
Although the risk score developed by Dr. Sen and colleagues accounts for various comorbidities, it may not apply equally to all patients. “As I understand it, they’re just using migraine with aura as a single factor,” said Dr. Caplan. Variables such as prolonged aura, frequent episodes, and aura-related deficit are associated with increased risk of stroke, but the risk score does not examine these factors.
Patients with severe, long-lasting attacks or attacks that involve weakness or aphasia should receive prophylactic treatment to prevent vasoconstriction, such as verapamil (), said Dr. Caplan. Antithrombotic agents such as aspirin also may be appropriate prophylaxis. Whether effective treatment of migraine with aura decreases the risk of stroke remains unknown.
SOURCE: Trivedi T et al. ISC 2020. Abstract WMP117.