REPORT FROM THE 2009 AAN ANNUAL MEETING – An internet survey has been used to estimate the global prevalence of chronic migraine, defined as >15 headache days per month and a clinical diagnosis of migraine (Varon et al. AAN 2009; abstract P06.001).

Participants were identified from a list of people who had previously agreed to participate in a health survey. Of 501,169 randomly selected email addresses, 120,478 people responded from eight countries in North America and Europe (24% response rate).

A majority of respondents in all countries were female (range 56% in Belgium to 81% in the U.S.). The mean age ranged from 32 (Spain) to 45 (Canada) years.

For female respondents, the prevalence of migraine was 4.36% in the U.S., 4.11% in Canada, 3.58% in France, 3.18% in Spain, 2.59% in Belgium, 2.22% in the Netherlands, and 1.86% in Germany. The reported prevalence of migraine in males was < 1% in all countries.

This is the first internet-based global survey conducted for migraine. The authors noted that the survey methodology may over- or underestimate the true prevalence of migraine.

Previous studies have generally reported higher prevalence rates. The American Migraine Prevalence and Prevention study (n=162,576) used mail-in questionnaires and reported a migraine prevalence of 12% (female 17.1%, male 5.6%) (Diamond et al. Headache 2007; 47: 355-363). A telephone survey in Germany (n=7341) found a one-year prevalence of 10.6% (Radtke & Neuhauser. Headache 2009; 49: 79-89). The 1998/1999 National Population Health Survey in Canada estimated the adult prevalence of migraine as 7.9% (females 11.7%, males 3.8%) (Martin S. CMAJ 2001; 164: 1481).

Comment:

Dr. Selchen: This study reports a  prevalence rate for chronic migraine  (greater than 15 headache days per month and a diagnosis of migraine) in the order of 4% for women and less than 1% for men. The number for women is surprising given the typically reported prevalence rates for migraine (10-15%). However, the methodology used, as noted by the authors, could result in a non-representative sample. The same authors in another poster (Kawata et al. AAN 2009; abstract p06.002) observed that patients with chronic migraine had less education, lower income and more unemployment then patients with episodic migraine.