The burden of headache disorders in the Eastern Mediterranean Region, 1990-2016: findings from the Global Burden of Disease study 2016

Headache, with the global prevalence of 47%, is one of the most common neurological disorders [1] Headache can be a secondary symptom of an underlying conditions (e.g. intracranial neoplasms, epileptic seizures, and intracranial infections); however, in most cases it is a primary and non-fatal disorder [2, 3]. Primary headaches such as migraine, tension-type headache (TTH), and cluster headache, although non-fatal, cause substantial disability and economic cost [4‐7].

Global Burden of Diseases, Injuries and Risk Factors study (GBD) is a comprehensive worldwide epidemiologic study being performed since 1990 [8, 9]. Estimation of years lived with disability (YLDs) and prevalence of diseases were among the main objectives of GBD [4]. In GBD 2000, for the first time, migraine was included as the only headache subtype. Since then, TTH was added to the GBD study, and some of the limitations in the previous estimates were addressed by using more comprehensive and reliable epidemiologic data based on population-based surveys from countries without previous available data [4]. GBD 2016, provided more accurate estimations of prevalence and burden of headache by countries, regions, and super regions [4].

According to GBD 2016, prevalence of headache disorders was variable across different geographic regions. For example, migraine was less frequent in African and Western Pacific WHO regions and TTH was less frequent in African region. However, the overall global all-age prevalence of migraine and TTH were estimated to be 14.1% (95% uncertainty interval [UI] 13.5–14.8%), and 25.6% (95% UI 23.1–28.4) respectively in 2016. Although prevalence of headache is an important epidemiologic measure, the burden of disability related to headache, as measured by YLD, is more informative for health policy making. Globally, migraine, with 45,121,909 YLDs (95% UI 29,045,835-62,826,904), and TTH, with 7,195,122 YLDs (95% UI 4,614,628-10,499,903), were the second and 28 leading causes of disability.

Despite the considerable burden, headache disorders are still underestimated and underdiagnosed [1, 10]. A study has estimated that the headache diagnosis rate is under 40% [11], which leads to a high undertreated rate. Effective treatment for most primary headache cases can be provided by primary health service and with low cost [11]; therefore, improvement of the diagnosis and treatment rate will substantially reduce the burden of headache.

GBD 2016 emphasized that primary headache disorders are an important health priority. Estimating the burden of headache is the first step to implement further measures to reduce its burden such as educating health care providers, developing primary care management, and allocating resources. In this study, we reported the prevalence and burden of primary headache disorders (including migraine and TTH) in Eastern Mediterranean Region (EMR) countries from 1990 to 2016 using data and methods of the Global Burden of Diseases, Injuries, and Risk Factors Study 2016.

This is the first study to investigate the prevalence and burden of headache in EMR. Our study provides a comprehensive assessment of the values and trends of prevalence and burden of primary headache disorders in EMR countries and their trends from 1990 to 2016. Our findings are of great value to health professionals and their efforts to reduce the burden of headache in the region. Indeed, our results could be used for planning and implementing programs to address this burden.

From 1990 to 2016, despite the overall consistent age-standardised YLD rates of headache, the all-age YLD rates and the total number of people suffering from headache has substantially increased. This finding is consistent with the global growing burden of non-communicable diseases [4]. Consistent age-standardised YLD rates along with the increase of number of people affected by headache indicates the role of population growth and ageing as the main factors of the increase in the burden of headache disorders.

Burden of headache was generally higher in the EMR countries compared to global average. Risk factors for progression of episodic migraine to chronic migraine can explain a part of the higher burden of headache in the EMR. Studies suggest that primary chronic migraine is rare, and chronic migraine usually progresses from episodic migraine. Gradual increase in frequency of episodic migraine attacks progresses to chronic migraine with an annual rate of 2.5% [29, 30]. The most important risk factors for progression of episodic migraine to chronic migraine are medication overuse for migraine attacks, obesity, depression, anxiety, and stressful life events [31, 32]. The higher rates of depression and anxiety in the EMR compared to the rest of the world can play a role in the higher burden of migraine in this region. In 2013, mental disorders contributed to 19.0% of non-fatal burden in the EMR, in comparison to 17.4% of global non-fatal burden [33]. Stressful life events can be another contributor of the higher burden of migraine in the EMR. For example, countries with ongoing or recent conflicts such as Palestine, Iraq, Yemen, Sudan, and Afghanistan had the highest observed than expected age-standardised YLD rates of migraine on the basis of their SDI. However, given the limited data sources from the EMR countries, the role of risk factors of chronic migraine in higher burden of headache in the EMR should be interpreted cautiously.

The EMR had greater than expected age-standardised YLD rates on the basis of SDI for headache, and the gap between observed and expected rates remained generally unchanged from 1990 to 2016. In contrast, worldwide observed age-standardised YLD rates were lower than the expected values during the same period. Constant high ratio of age-standardised YLD rates relative to that expected in the EMR suggests poor performance of health service in terms of headache outcomes relative to the development status, reflecting a need for additional attention to the reasons of this underperformance and policy implications for health reforms in EMR countries.

YLD rate of migraine and TTH were highest between ages 25 and 54 years, which is consistent with the literature [34]. However, the burden of headache is still considerable in 5–24 and 55–74 year old age groups.

Estimated all-age prevalence rates for migraine and TTH in the EMR were higher compared with the global rates. A review on epidemiological studies between 1988 and 2005 estimated that the global prevalence of migraine and TTH were 10% and 38% respectively [1]. However, studies have shown a wide variation in the prevalence of primary headache disorders, partly because of the differences in methodology. Particularly for TTH, case definition has been a challenge; for example, variation in frequency and duration of TTH and its overlap with migraine may have led to differences in prevalence [35]. Disparity in prevalence rates, reported by studies with different methodology, made them non-comparable over time and across geographic areas. GBD, however, is a systematic approach that has the important advantage of providing comparable prevalence and burden over time and by geography.

Our findings have important health service implications. The significant and increasing non-fatal burden of headache inform policy makers and health care providers of EMR countries that primary headache should be a health care priority, and intervention strategies focusing on improvement of diagnosis and treatment of headache must be implemented. Primary headache is one of the leading causes of disability; meanwhile, effective and low-cost treatments are available for most patients with primary headache (including patients with migraine and TTH). In most cases, patients with primary headaches can be diagnosed and treated by the primary health-care physicians. Moreover, high prevalence of primary headaches across a wide range of ages necessitates interventional strategies that, in the first place, target the primary health service. Better education of health-care professionals, especially those who work in primary health-care services, is the most essential part of interventional strategies to reduce the burden of headache. Health-care professionals should be educated to properly diagnose and treat patients with primary headache disorders. Providing diagnostic and treatment guidelines, especially for non-expert healthcare providers is also a practical method especially for the low-income countries [11].

The implication of these findings is that investment in interventional strategies for diagnosis and treatment of headache will lead to a considerable reduction in the healthcare costs and the burden of headache. Our study calls for more population-based surveys investigating the prevalence and severity of primary headache disorders in EMR countries. Population-based and disease-specific surveys providing better data coverage on headache epidemiology in EMR are needed for more accurate estimates of primary headache burden in the region.

Quality of life and financial impacts are important contributors of the burden. For example, with a mean per-person annual cost of €1222, the annual total cost of migraine has been estimated to be €111 billion in Europe in 2009 [36]. Another study estimated the mean per-person annual cost of episodic and chronic migraine at $2649 and $8243 in the US in 2013 [37]. Furthermore, studies from Sweden [38], then US [39], and the UK [40] have reported that migraine has a considerable negative effect on family quality of life. In this study, although we estimated the most important contributors of the headache’s burden, we did not capture its costs and quality of life.

This study has some limitations. The main concern is the lack of adequate data and poor quality of the available data from the EMR. Since accessible data sources for prevalence of migraine and TTH in EMR are scarce, we were able to use data from only few of the EMR countries. In comparison to GBD 2013, with prevalence data from only one EMR country (Iran), GBD 2016 is an obvious improvement; however, there is still no reliable data from most of the EMR countries. Unfortunately, the region is facing several health challenges which divert attention from headaches in the mind of many health professionals. However, we hope that our study will increase the attention to this large burden and lead to improved data. Second, although we estimated prevalence and YLDs of the primary headache disorders with considerable burden (including migraine, TTH, and MOH - as a sequel of the first two syndromes), we could not include all primary headache disorders classified in ICD-10 classification [41]. Cluster headache, for example, was the most important headache syndrome that we did not capture in this GBD iteration.

Findings from this study show that primary headache disorders are a large cause of disability in the EMR. Despite generally unchanged age-standardised YLDs, YLD numbers increased substantially between 1990 and 2016 in the EMR-mostly due to the population growth and ageing. Our findings inform policy makers of the EMR countries that headache is a health care priority, and preventive and management interventions must be implemented to address the growing burden of headache in this region. More studies are needed to provide more accurate data on the prevalence and severity of primary headache disorders in EMR as well as more efficient preventive and management methods to reduce the burden of headache.