Prevalence of frequent headache in a population sample

Purpose.-Patients with daily or near-daily headaches are commonly seen in n eurology practices and in headache subspecialty centers, but there is littl e information on the prevalence of this condition in the general population . We present the first US-based study describing the. prevalence and charac teristics of frequent headache in the general population. Methods.-In Baltimore County, Maryland, 13 343 individuals 18 to 65 years o f age were selected by random-digit dialing and interviewed by telephone ab out their headaches. Subjects reporting 180 or more headaches per year were classified as having frequent headache. Three mutually exclusive subtypes of frequent headache were identified: frequent headache with migrainous fea tures, chronic tension-type headache, and unclassified frequent headache. Results.-The overall prevalence of frequent headache was 4.1% (5.0% female, 2.8% male; 1.8:1 female to male ratio). Frequent headache was 33% more com mon in Caucasians (4.4%) than in African Americans (3.3%). In both males an d females, prevalence was highest in the lowest educational category. Among frequent headache sufferers, more than half (52% female, 56% male:) met cr iteria for chronic tension-type headache, almost one third (33% female, 25% male) met criteria for frequent headache with migrainous features, and the remainder (15% female, 19% male) were unclassified. Overall, 30% of female and 25% of male frequent headache sufferers met International Headache Soc iety (IHS) criteria for migraine (with or without aura). Conclusions;-Frequent headache is common in the general population and is m ore prevalent in Caucasians and in those with less than a high school educa tion. Chronic tension-type headache is more common than frequent headache w ith migrainous features, though the latter is more disabling. Although more common in females than males, the female preponderance of frequent headach e is less marked than in migraine. The sex ratio varies by frequent headach e subtype.