Migraine is a common and disabling health problem among adult Americans. Surveys from the U.S. and elsewhere suggest that 6% of men and 15% to 17% of women experience migraine headaches. These headaches result in significant disability and work loss; estimated aggregate indirect costs to employers in theU.S. for reduced productivity due to migraine range from $6.5 billion to $17 billion annually. Patterns of medical care for the treatment of migraine...