SAN FRANCISCO – Women who have migraine with aura could be at increased risk for ischemic stroke, Leah MacClellan said at the 32nd International Stroke Conference.
She reported findings from a population-based case-control study of 386 women aged 15–49 years who presented with a first, nontraumatic ischemic stroke and 614 controls matched for age, race, and region.
The investigators stratified the odds of stroke among women with a history of migraine with aura, compared with women who did not have a history of migraine, by the presence of hypertension, diabetes, or myocardial infarction.
The associations were strongest among those with no history of these classic stroke risk factors, Ms. MacClellan explained at the conference, which was sponsored by the American Stroke Association.
For example, the odds ratio for stroke in those with migraine plus aura versus those with no history of migraine was 0.8 in those with hypertension, compared with 1.7 for those without hypertension; 1.2 in those with diabetes, compared with 1.5 in those without diabetes; and 0.2 in those with a history of MI, compared with 1.6 in those with no history of MI, said Ms. MacClellan of the University of Maryland, Baltimore. All associations were statistically significant.
“This finding is important because it suggests migraine might contribute to stroke independent of these classic risk factors,” she said.
A similar analysis stratifying stroke risk based on current smoking and oral contraceptive use in women with migraine plus aura, compared with women with no history of migraine, showed the associations between migraine with aura and stroke were the same regardless of smoking or OC use. However, the interaction between smoking and OC use was shown to be important, she reported.
Compared with women with migraine plus aura alone, those who smoked and had migraine plus aura had a significant 2.3-fold increased risk of stroke, as did those with migraine plus aura who used oral contraceptives. Women with migraine plus aura who smoked and also used OCs had a significant 7.3-fold increase in the odds of stroke.
“This finding is important because these are modifiable risk factors,” Ms. MacClellan noted.
Another finding of note from this study was that onset of migraine with aura in the past year was associated with increased stroke risk. Those with onset in the past year, compared with those with no history of migraine, had a significant 6.7-fold increased risk of stroke.
Those with a migraine history of more than 12 years had a non-statistically significant 1.4-fold increase in stroke risk. This finding contrasts with those from at least one other study showing that long-term migraine history was associated with increased stroke risk, she said.
The possibility that unrecognized disorders might explain the association between recent migraine onset and stroke risk in the current study warrants additional study, she said during a discussion that followed her presentation.
There was no evidence in the current study of a role for patent foramen ovale in mediating the association between migraine with aura and stroke, nor was there any evidence for preferential infarct location in terms of anterior and posterior circulation in those patients with migraine plus aura.
Patients in this study were identified from discharge data from 59 hospitals, and all had stroke that was confirmed by CT or MRI. Controls were ascertained by random digit dialing.
Migraine with aura was defined as headache with aura at least twice per year, with spots, lines, flashing lights, or loss of vision occurring around the time of the headache. Migraine without aura was defined as at least five headaches per year with nausea, vomiting, or sensitivity to light during headache, and no history of visual aura.
Migraine with aura was reported by 38% of patients and 29% of controls. The percentage with migraine without aura was similar in the two groups; thus the current analysis focused only on migraine with aura.