PREVALENCE OF MIGRAINE HEADACHE IN CANADA - A POPULATION-BASED SURVEY

Background, The aim of the present study was to estimate the prevalence of migraine headache among Canadian adults (aged greater than or equal to 18 years) and analyse variation by age, gender, household income and province of residence. Methods. A population-based survey was undertaken using telephone interviews with 2922 adults who were randomly selected from households across Canada by stratified regional sampling. The questionnaire asked about frequency and characteristics of headaches experienced and other symptoms. The diagnostic criteria of the International Headache Society were used to classify people as migraineurs (with or without aura), headachers or non-headachers. Results. Of 8921 random calls to households, 4235 were eligible and 2922 interviews were successfully completed (response rate 66%). The prevalence of migraineurs, headachers and non-headachers among males was 7.8%, 76.1%, 16.1% and among females was 24.9%, 65.6%, 9.4%. For females prevalence appears to increase with age, peaking at 40-44 years and declining thereafter. Sex-specific prevalence for males and females, controlling for age, was significantly lower in the province of Quebec compared to other provinces. We found no association between migraine prevalence and household income. Of 500 people classified by IHS criteria as migraineurs only 232 (46%) reported any migraine diagnosis by a physician. Conclusion. We estimate that 2.6 million adult females and 0.8 million adult males in Canada are migraineurs, but only half are likely to have been diagnosed by a physician. Contrary to a recent US survey, people from lower income households in Canada are not at greater risk of migraine. The lower prevalence of migraine in Quebec was unexpected and remains unexplained, but it may be influenced by language/translation problems.