Are some patient-perceived migraine triggers simply early manifestations of the attack?
To study the agreement between self-reported trigger factors and early premonitory symptoms amongst a group of migraineurs in both spontaneous and pharmacologically provoked attacks.Fifty-three subjects with migraine with and without aura, with ≤ 22 headache days/month, with spontaneous premonitory symptoms associated with migraine attacks were recruited nationally. A detailed history was taken by a study investigator to confirm diagnosis and extended phenotyping was performed to identify patient-reported triggers for migraine attacks, premonitory symptom phenotype and headache characteristics, using a standardised physician-administered questionnaire. The same subjects were exposed to a 0.5 mcg/kg/min nitroglycerin infusion over 20 min, to determine if similar migraine symptoms could be triggered. The triggered attacks were phenotyped in the same way as spontaneous ones. Percentage agreement and Cohen’s kappa measure of agreement were used to identify concordance between patient-reported triggers and the corresponding spontaneous and triggered premonitory symptoms. Percentage agreement of > 60% and/or a kappa value > 0.3 with P