Headache disorders and public ill-health in India: prevalence estimates in Karnataka State

Background: Primary headache disorders are among the commonest disorders, affecting people in all countries. India appears to be no exception, although reliable epidemiological data on headache in this highly populous country are not available. Such information is needed for health-policy purposes. Our aim was to estimate the prevalence of each of the headache disorders of public-health importance, and examine their sociodemographic associations, in urban and rural populations of Karnataka, south India. Methods: In a door-to-door survey, 2,329 biologically unrelated adults (aged 18-65 years) were randomly sampled from urban (n = 1,226) and rural (n = 1,103) areas in and around Bangalore and interviewed by trained researchers using a pilot-tested, validated, structured questionnaire. ICHD-II diagnostic criteria were applied. Results: The observed 1-year prevalence of any headache was 63.9 %, with a female preponderance of 4:3. The age-standardised 1 year prevalence of migraine was 25.2 %; prevalence was higher among females than males (OR: 2.1 [1.7-2.6]) and among those from rural areas than urban (OR = 1.5 [1.3-1.8]). The age-standardized 1 year prevalence of TTH was 35.1 %, higher among younger people. The estimated prevalence of all headache on >= 15 days/month was 3.0 %; that of pMOH was 1.2 %, five-times greater among females than males and with a rural preponderance. Conclusions: There is a very high 1 year prevalence of migraine in south India (the mean global prevalence is estimated at 14.7 %). Explanations probably lie in cultural, lifestyle and/or environmental factors, although the observed associations with female gender and rural dwelling are usual. Levels of TTH, pMOH and other headache on >= 15 days/month are similar to global averages, while the very strong association of pMOH with female gender requires explanation. Until another study is conducted in the north of the country, these are the best data available for health policy in a population of over 1.2 billion people.