Respondents were asked to report the average number of days that they experienced headache in a week, month, or year. They were also asked if they experienced pain-free intervals find more between attacks. Respondents were asked if they experienced symptoms with “severe” headache including nausea; vomiting; unilateral head pain; pulsating or

throbbing pain; sensitivity to light; sensitivity to noise; blurring of vision in association with headaches; presence of shimmering lights, circles, other shapes, or colors before the eyes before the start of the headache; and presence of numbness of lips, tongue, fingers, or legs before the start of the headache. Respondents were asked to report average pain intensity of severe headaches as: extremely severe pain, severe pain, moderately severe pain, or mild pain. Responses to these items were used to assign headache type based on the ICHD-2. Use of these items to assign a diagnosis was validated in a population sample of subjects with migraine and other types of headache.[7] The items exhibited a sensitivity

of 100% and specificity of 82.3% for the diagnosis of migraine. Although this diagnostic module was not revalidated using ICHD-2 criteria, the migraine criteria remained essentially unchanged relative to ICHD-1 criteria. Migraine and PM diagnoses were derived by applying modified ABT-888 ICHD-2 criteria. Respondents satisfied Criterion 1 CYTH4 if they reported one or more of the following associated with headache: severe or extremely severe pain, unilateral headache, or pulsatile or throbbing pain. Respondents satisfied Criterion 2 if they reported one or more of the following associated with headache:

nausea or vomiting, photophobia and phonophobia, or visual or sensory aura. A migraine diagnosis was assigned if a respondent met both Criteria 1 and 2. A diagnosis of PM was assigned if a respondent met either Criterion 1 or 2. If neither of these criteria were met, respondents were assigned with “other severe headache.” This group may logically capture cluster headache, tension-type headache, and other nonmigrainous forms of headache that respondents subjectively rated as “severe. Headache-related disability was assessed with the Migraine Disability Assessment Questionnaire (MIDAS).[33] The MIDAS is a self-administered 5-item questionnaire that assesses days of missed activity or substantially reduced activity due to headache in the preceding 3 months in 3 domains: schoolwork/paid employment, household work or chores, and nonwork (family, social, and leisure) activities. Responses are summed and fall into 1 of 4 grades of headache-related disability: little or none (0-5), mild (6-10), moderate (11-20), or severe (21-40).