What is chronic headache in the general population? The Akershus study of chronic headache

BACKGROUND: Studies of chronic headache including both primary and secondary causes from the general population is lacking. AIMS: To provide prevalence data on chronic headache. MATERIALS & METHODS: We studied chronic headaches defined as headache 15 days per month on average for at least 3 months in the general population. An age and gender stratified random sample of 30,000 persons aged 30-44 years received a mailed questionnaire. Those with self-reported headache on 15 days or more within the last month and/or headache on more than 180 days within the last year were invited to an interview and examination by a neurological resident. The criteria of the International Classification of Headache Disorders were applied. RESULTS: Chronic headache occurred in 3.71% of the general population.Women had chronic headache twice as often as men. About half of those with chronic headache also had medication overuse, irrespectively of the types of chronic headache. Secondary chronic headaches attributed to chronic rhinosinusitis, head injury, whiplash injury and cervicogenic headache were relatively frequent, i.e. from 1 of 300 to 1 of 600 persons from the general population. DISCUSSION: Primary and secondary chronics headaches should not be ignored. CONCLUSION: Primary and secondary chronic headaches are common in the general population.