Global epidemiology of migraine and its implications for public health and health policy

Migraine is one of more than 200 headache disorders but stands out among these as a major cause of population ill health. In migraine epidemiology, the key variable is prevalence, but, from the perspective of public health, prevalence is uninformative without burden estimates. Here, we discuss how migraine epidemiology, from a quite recent start, has evolved into the respectable though imperfect science of today, but with the legacy that much of the large corpus of older literature is of questionable reliability. Newer studies have benefited from a universally accepted definition of migraine, while methodological developments have broadened the scope of migraine caseness, and published guidelines address important methodological issues. In the light of these developments, we question the apparent increase in migraine prevalence over time, offering explanations as to why this may be illusory. We suggest that the current best estimates are that global migraine prevalence is 14–15%, and that migraine accounts for 4.9% of global population ill health quantified in years lived with disability (YLDs). These evaluations are probably under-quantified rather than over-quantified, and YLDs are not a comprehensive measure of migraine-attributed burden. Despite these uncertainties, such high estimates of population ill health have clear implications for health policy. Here, Timothy Steiner and Lars Stovner discuss the progression of migraine epidemiology over the last seven decades and question the apparent increase in migraine prevalence over time. Key points Migraine is one of more than 200 recognized headache disorders but, as a major cause of global population ill health, stands out from all others in the context of public health. Although prevalence is the key variable in migraine epidemiology, prevalence estimates, from the perspective of public health, are uninformative without associated burden estimates. Migraine epidemiology is a young and evolving science, and, with an accepted definition of migraine available only since 1988, much in the large corpus of older literature is of questionable reliability. Accordingly, the apparent increase in migraine prevalence over the past three decades may be illusory. The current best estimate of global migraine prevalence is 14–15%, and, in terms of burden, migraine accounts for 4.9% of global ill health, quantified as years lived with disability. These evaluations are still attended by uncertainty and are probably under