To the Editor: Dr Kurth and colleagues1 reported the results of their study of the association between migraine and risk of cardiovascular disease (CVD). We believe that several factors limit the interpretability of their findings.
While the authors state that exposure misclassification would have led to underestimation of the migraine-CVD association, this is not certain. There were at least 2 types of potential errors in classifying study participants. First, participants were asked whether they had ever experienced a migraine headache or had experienced a migraine headache during the past year. An affirmative response led to further questioning and classification. Women who did not recognize their headaches as being migraines would have been misclassified as having no history of migraine, which may account for the study's low prevalence of active migraine (13.0%). Many patients who believe they have sinus headache actually meet International Headache Society criteria for migraine.2 Second, the question used to identify aura would have been sensitive to premonitory symptoms, which may be present in more than 60% of patients with migraine.3 It is probable that some participants were misclassified as having “active migraine with aura.” The combined effect of these 2 potential classification errors is not obvious.
Young WB, Shaw JW. Association Between Migraine and Cardiovascular Disease in Women. JAMA. 2006;296(22):2677–2678. doi:10.1001/jama.296.22.2677-a
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