If it were needed, more evidence of the disconcerting under-treatment of headache
disorders has come from the Eurolight study [1]. The topic is not new. Twenty years
ago, the International and American Headache Societies jointly voiced their dismay
at the inadequacies of health care for headache [2]. In 2006, the European Headache
Federation and World Headache Alliance described migraine as a “forgotten epidemic”
[3]. Meanwhile, in 2003, the Global Campaign against Headache [4–6] engaged the World
Health Organization (WHO) as partner in this cause [7], embarking on a worldwide action
programme which began by assessing the magnitude of headache in the world [4, 8].
In 2011, WHO’s global survey of headache disorders and resources, a Global Campaign
project, laid bare the scale and scope of under-treated headache everywhere, and its
consequences [9]. WHO wrote, in a message sent inter alia to the world’s Ministries
of Health: “This first global enquiry into these matters illuminates the worldwide
neglect of a major public-health problem, and reveals the inadequacies of responses
to it in countries throughout the world” [9]. No words could be clearer but, to make
sure, WHO repeated the message soon after [10].
Eurolight was a cross-sectional survey of over 8000 participants, conducted by multiple
partners (scientific and lay) in 10 European countries [11]. A considerable strength
of this study, apart from its size and geographical scope, was the use in all countries
of the same questionnaire [12], a derivative of the HARDSHIP questionnaire already
employed in many different countries, cultures and translations [13]. Also a strength
was its scope of enquiry, simultaneously into migraine, tension-type headache (TTH)
and medication-overuse headache (MOH), the three headache disorders of major public-health
importance. This provided a broad view of headache in Europe. The different sampling
methods employed by the countries in Eurolight produced samples that varied in their
representativeness of the general population, arguably a strength in that it brought
data into the survey from diversely-sourced samples [11, 12].
The new report analyses Eurolight data for indicators of adequacy of medical care
[1]. The focus is on migraine, and the findings are depressing. Among 1175 participants
in the 10 countries reporting frequent migraine – on more than five days per month,
indicating unambiguous need for preventative medication – fewer than 20% had seen
a health-care professional (general practitioner [GP] or specialist). In most countries,
fewer than 10% were receiving what might be considered adequate acute treatment, and
even smaller proportions had the preventative medication for which they were clearly
eligible. Participants who had managed to make contact with specialists generally
received better care by these indicators, which might be expected. Those seeing GPs
were less well served, and those entirely dependent on self-medication – the large
majority – fared poorly. In other words, the authors conclude, in wealthy Europe,
too few people with migraine consult physicians, and migraine-specific medications
are used inadequately even among those who do [1]. Is there hope at all for people
with headache in less well-resourced countries?
The Eurolight report comes soon after publication of the latest (2016) Global Burden
of Disease (GBD) study [14]. “The most comprehensive worldwide observational epidemiological
study to date” [15], GBD has been performed reiteratively since 1990, with estimates
of health loss due to disease a principal objective [16]. Its findings, informing
national health policies, offer a rational basis for priority setting and resource-allocation,
driving service organisation and delivery to meet assessed needs. GBD now revises
its estimates annually as it continuously develops and refines the methodology of
disease-burden estimation and its expression as premature mortality (years of life
lost: YLLs) and disability (years lived with disability: YLDs). At the same time,
updated estimates take account of new epidemiological evidence as it continues to
become available.
Since migraine was first included in GBD, it has ascended the ranks of top causes
of YLDs worldwide, from its debut at 19th in GBD 2000 [17] to seventh in GBD 2010
[18, 19] and sixth in GBD 2013 [20, 21]. This persistent rise is not indicative of
increasing prevalence: it follows the collection and assimilation into GBD of ever
better data as new population-based studies have slowly filled the large knowledge
gaps, which as recently as 2007 related to more than half the world’s population [22].
With better knowledge, empirical data have replaced many of the assumptions underlying
the earlier GBD estimates, and, as YLD calculations became prevalence-based rather
than reliant on the less-easily ascertained incidence and duration, estimates have
gained in reliability. In GBD 2015, migraine dropped back to seventh among causes
of YLDs, partly because of revised estimates for other disorders, but, being notably
age-related, it was third in both males and females aged 15–49 [23].
GBD 2016 offers sobering findings for those affected by or who care about migraine
[14]. At level two of GBD’s disease hierarchy, neurological disorders collectively
account for 8.6% of all YLDs in the world, and come fourth in the disability ranking
(behind mental and substance use, “other non-communicable” and musculoskeletal disorders).
At level three, headache disorders are the cause of more than three quarters of all
neurological YLDs (6.5% of all YLDs), despite that neurological disorders include
epilepsy, Alzheimer disease and other dementias, Parkinson’s disease, multiple sclerosis
and motor neuron disease. At level four, migraine now takes second place, responsible
for 5.6% of all YLDs in the world, behind only low back pain (7.2%) (Table 1).
Table 1
Top 10 level-4 causes of disability in GBD 2016 (global, both sexes, all ages)
Low back pain
Migraine
Age-related hearing loss
Iron-deficiency anaemia
Major depression
Neck pain
Other musculoskeletal disorders
Diabetes
Anxiety disorders
Falls
There is worse. In the age group 15–49 years, migraine is the top cause of YLDs [14]
(Table 2). Let us not forget that these are the productive years, when education is
completed, families formed, children raised, careers built and prospects for the whole
remainder of life established. Whatever impact migraine-attributed disability may
have more generally, during these years it is greatly magnified.
Table 2
GBD 2016: Years lived with disability (YLDs) attributed to migraine by gender, age
and region (from [14])
Region
Gender
Age range (years)
% of total YLDs(95% CI)
Rank
Global
Both
All15–49
5.6 (4.0–7.2)8.2 (6.0–10.6)
21
M
All15–49
4.3 (3.1–5.5)6.4 (4.6–8.2)
32
F
All15–49
6.8 (4.9–8.8)9.8 (7.1–12.7)
21
North America
Both
All
4.8 (3.5–6.1)
5
Latin America and Caribbean
6.7 (4.9–8.6)
2
Western Europe
6.2 (4.5–7.9)
2
Central and Eastern Europe and Central Asia
6.0 (4.4–7.7)
3
South Asia
6.5 (4.6–8.5)
2
SE and East Asia and Oceania
4.6 (3.3–6.0)
4
North Africa and Middle East
6.7 (5.0–8.6)
2
Sub-Saharan Africa
4.6 (3.2–6.1)
3
There is a ready explanation for the apparently steep rise in migraine since GBD 2015,
conducted a year earlier: it lies with MOH. GBD 2015 regarded MOH as a separate disease
[23]. While MOH is relatively uncommon (prevalence estimates vary around the world
but are mostly in the range 1.5–3% [24, 25]), it is highly disabling, by definition
characterised by headache on 15 or more days per month [26]. GBD 2015 placed it 18th
among the causes of YLDs [23]. Nosologically, MOH is undoubtedly a distinct disease
[26], but aetiologically it is a complication arising from mistreatment of other headache
disorders, principally migraine and to a lesser extent TTH: it does not occur otherwise
[26]. In GBD 2016, the decision was made that burden attributed to MOH would be more
correctly attributed to the antecedent disorders, in due proportion (73.4% to migraine,
26.6% to TTH, from a meta-analysis of three studies [27–29]).
Not everybody may agree with this, but there is both logic and purpose in recognising
MOH as one of the sequelae (health states) of the antecedent headache disorder. In
GBD terms, therefore, migraine is associated with three potential health states, each
occurring with measurable probability (established in population-based studies): the
ictal state (during an attack, with its symptoms), the interictal state (between recurrent
attacks), and MOH. All three contribute to the disability burden of migraine, and
all three contributions should be duly recognised. (We noted earlier that GBD does
not consider disability associated with the interictal state of headache disorders
[21], although significant interictal burden is reported by many people with migraine
[30]).
From GBD 2016 it is more evident than ever that headache disorders have a very large
detrimental effect on public health. Table 2 shows that migraine is a major contributor
to disability throughout the world, in both high- and low-income countries [14]. It
is worth noting that, of the 21 regions into which GBD divides the world, five are
still without any data on headache and more have only scarce data. Furthermore, most
data are from adults, with relatively few studies reporting on children and adolescents.
Nevertheless, headache disorders are, manifestly, an egregious cause of health loss.
Why, then, when efficacious and cost-effective treatments exist [31, 32], do health
services almost everywhere leave them side-lined [9, 10, 33]? Will health politicians
finally take notice, now that migraine is top of the heap?
Looking forward, and not to end on an impliedly negative note, we remind researchers
that further population-based studies are needed to fill the remaining knowledge gaps.
Quality in these is all-important: published methodological guidelines [34] and instruments
[13] are available, and surveys should follow and adopt these. Ultimately, if studies
contributing to GBD are standardized, future iterations of GBD may not only show the
relative importance of headache in global public health but also monitor the benefits
of improvements in headache care, new treatments and societal change.