GBD 2015: migraine is the third cause of disability in under 50s

摘要

The answer depends on how headache is measured. The question, however, is an important one. It is at the basis of health policy, prioritisation and the due allocation of health resources to headache care and the mitigation of its clinical sequelae. From this perspective, prevalence alone is not highly informative: it is the burdens arising from headache disorders that dictate their impact on public health. These burdens are multiple, diverse and partly invisible [1]. Methods do not yet exist to measure them all [1], but the focus meanwhile has been on disability. It is to this, primarily, that health, quality of life, productivity and financial security are hostage. So how much headache-related disability is there in the world? Estimates of disability due to disease are a principal objective of the Global Burden of Disease (GBD) studies, performed reiteratively since 1990 and described now as 鈥渢he most comprehensive worldwide observational epidemiological study to date鈥?[2]. GBD 1990 was initiated by the World Bank and GBD 2000 by the World Health Organization; subsequently, GBD has been led by the Institute for Health Metrics and Evaluation [3], and financially supported by the Bill and Melinda Gates Foundation. GBD uses a number of metrics: among these, disability is measured in years lived with disability (YLDs) and early mortality in years of life lost (YLLs); disability-adjusted life years (DALYs) are the summation of YLDs and YLLs. Migraine first featured in GBD 2000 [4], and over 13years ascended the ranks of top causes of YLDs worldwide, from 19th in GBD 2000 [4] to seventh in GBD 2010 [5, 6] and sixth in GBD 2013 [7, 8]. Meanwhile, of the other headache disorders of public-health importance, tension-type headache (TTH) was introduced in GBD 2010 [5] and medication-overuse headache (MOH) in GBD 2013 (and ranked 18th highest cause of YLDs) [7]. GBD 2013 established headache disorders collectively as the third highest cause of YLDs [8]. The rise of migraine over these years is not indicative of increasing prevalence. While GBD is dependent on data from the entire world, headache epidemiology is a still-developing science [9]. Very large knowledge gaps existed in 2000, particularly in regions outside the Americas and Western Europe [10]. Filling these gaps became the first priority of the Global Campaign against Headache after its launch in 2004 [11鈥?span class="CitationRef">13]. Collaborating in all subsequent GBD studies, the Global Campaign has informed them by conducting new population-based surveys in Georgia, Russia, China, Nepal, South India, Saudi Arabia, Pakistan, Zambia, Ethiopia and Morocco [14]. This concerted data-collection effort has allowed much better estimates from GBD 2010 onwards. With empirical data replacing many of the assumptions underlying the earlier GBD estimates, and an approach to YLD calculation based on prevalence rather than incidence and duration as in GBD 2000, estimates became possible by country rather than by large world regions. GBD 2015 has now been published [15, 16]. In this latest iteration, a more systematic hierarchy has been adopted in the grouping of related causes of DALYs. Non-communicable disorders, at level 1, include neurological disorders at level 2; within the latter reside the individual headache disorders (migraine, TTH and MOH) at both levels 3 and 4. Future iterations of GBD may more logically group the headache disorders together at level 3, as we have done in the following analysis. There can be no doubt that migraine is a major contributor to public ill health in all countries, climes and cultures. Table2 shows it consistently ranked fifth to eighth among the top causes of disability in all world regions. Further, the notion that migraine is a disease preferentially affecting rich industrialised nations is dispelled by the comparison in Table2 between low- and high-income countries. It is worth adding here that GBD currently considers only the disability burden a