Migraine: Epidemiology, Burden, and Comorbidity.

Migraine affects an estimated 12% of the population. Global estimates are higher. Chronic migraine (CM) affects 1% to 2% of the global population. Approximately 2.5% of persons with episodic migraine progress to CM. Several risk factors are associated with the progression to CM. There is significant short-term variability in migraine frequency independent of treatment. Migraine is associated with cardiovascular disease, psychiatric disease, and sleep disorders. It is the second most disabling condition worldwide. CM is associated with higher headache-related disability/impact, medical and psychiatric comorbidities, health care resource use, direct and indirect costs, lower socioeconomic status, and health-related quality of life.