The International Burden of Migraine Study (IBMS): study design, methodology, and baseline cohort characteristics.

OBJECTIVE: To describe a survey methodology to evaluate headache characteristics and burden and to present baseline characteristics for the international cohort of survey participants. METHODS: A targeted, web-based methodology was used to recruit and survey subjects with migraine in 10 countries. Based on reported symptoms, subjects meeting ICHD-2 criteria for migraine were included; eligible subjects were classified as chronic (≥ 15 headache days per month) or episodic (< 15 headache days per month). Outcomes included sociodemographic and clinical characteristics, resource utilization, disability, health-related quality of life, anxiety, depression and productivity. RESULTS: Of 23,312 survey respondents, 11,897 were eligible and 9715 (81.7%) completed the survey; subjects were 81.5% female; 5.7% (n = 555) had chronic migraine. CONCLUSIONS: This is the first large international cohort of persons with chronic and episodic migraine studied using a web-based approach, a methodology well suited to the study of the burden of migraines.