Methodological Issues in Studying Trigger Factors and Premonitory Features of Migraine

OBJECTIVE: In this review, we focus on migraine as a chronic disorder with episodic attacks (CDEA). We aim to review methodological approaches to studying trigger factors and premonitory features that often precede a migraine attack. BACKGROUND: Migraine attacks are sometimes initiated by trigger factors, exposures which increase the probability of an attack. They are heralded by premonitory features, symptoms which warn of an impending attack. DESIGN/METHODS: We review candidate predictors of migraine attack and discuss the methodological issues and approaches to studying attack prediction and suggest that electronic diaries may be the method of choice. CONCLUSION: Establishing the relationship between antecedent events and headaches is a formidable challenge. Successfully addressing this challenge should provide insights into disease mechanisms and lead to new strategies for treatment. In the second paper in this series, we review the available literature on trigger factors and premonitory features.