by Günther Deuschl
It is not new that human disease is imposing a burden on the sufferers and a challenge for the physician. While neurologists are having the privilege being physicians and have the single patient in our focus of attention, health economists take a different view. Their thinking is focusing on the burden of disease for the society and its economic implications. They look at the costs of disease in different terms. The classical measures for the burden of disease are the costs in terms of disability-adjusted life years (DALYs) which are defined as the sum of years of life lost due to the disease (YLLs) and years lived with the disease (YLDs) accounting for reduced life time with good quality of life due to the disability. Another important measure is the Socio-demographic Index (SDI) reflecting economic and educational development. There is big science behind all these calculations which I will not go into detail here.
Many attempts have been made to quantify the disease burden for specific countries and diseases. By far the most prominent group to calculate the disease burden world-wide is an international consortium of Heath Economy Institutes around the globe which are orchestrated by the Institute for Health Metrics and Evaluation in Seattle, USA. Their report on the years 1990-2015 has been published in 2016 in the Lancet.1, 2 It is an admirable collection of data with a methodology as uniform as it can be, despite the heterogeneous sources. It is setting the current standards for health research.
In the November-issue of the Lancet Neurology (prepublished 2017/09/22, download:3) the data relating to neurologic disease have been separately analyzed by hundreds of authors under the leadership of Valery Feigin and Theo Vos.4 Data for the year 2015 were compared with 1990 to show the developments.5 What are the specific merits of this study?
This study has for the first time and at this high methodological level united all highly prevalent neurologic diseases under the header of neurologic disease: Stroke was included – currently listed under cardiovascular disease, brain cancers – listed under cancer, brain infections – listed under infectious disease. The result is showing the extraordinary burden that neurologic diseases cause to the world population and in particular to the inhabitants of Europe. It is shown that:
- Neurological diseases are the largest cause of DALYs in 2015: 250·7 million, equivalent to 10.2% of global DALYs.
- Neurological diseases are the second-largest cause of global deaths: 9·4 million, equivalent to 16.8% of global deaths.
- the most prevalent neurological disorders were headaches (2,527.3 million cases), Alzheimer’s disease and other dementias (46.0 mio), stroke (42.4 mio), epilepsy (23.4 mio), Meningitis (8.7 mio), Parkinson’s disease (6.2 mio), encephalitis (4.3 mio), multiple sclerosis (2.0 mio), brain cancer (1.21 mio), motorneurone disease (0.2 mio).
- Between 1990 and 2015, the number of deaths from neurological disorders increased by 36·7%, and the number of DALYs by 7·4%.
- These increases occurred despite strong decreases in age-standardised rates of death and DALYs of 26·1% and 29·7%, respectively; stroke and communicable neurological disorders were responsible for most of these decreases.
- Stroke rates were highest at middle levels of the SDI and lowest at the highest SDI. Communicable neurological disorders were the largest cause of DALYs in countries with low SDI. Most of the changes in DALY rates of neurological disorders with development were caused by changes in YLLs.
Such alarming numbers illustrate the complex decision situation of modern health and research policy and the needs to invest into neurologic research and patient care for the future:
- It is no longer that only academics warn that neurologic diseases will increase. This analysis documents that this process is currently underway and will further accelerate world-wide.
- Neurologic efforts and preventive efforts are successful as e.g. stroke rates are high in middle and low-income countries but lower in high income countries. This is underscoring that the mix of interventions including lifestyle changes (e.g., tobacco cessation, nutrition), preventive treatments (e.g. hypertonia treatment) and neurologic treatments (modern stroke medicine) leads to less disease burden. Such efforts need to be replicated in low and middle-income countries.
- It shows how important it is to classify neurological diseases under the appropriate heading in the ICD 11. Otherwise neurology will always be underestimated in its importance for the health system.
- The number of age-dependent diseases like Alzheimers’ and Parkinsons’ are high in high-income countries and increasing in low-income countries as they are increasing with longer life expectancy.
These insights should have fundamental consequences. The politicians can now see the full extent of the burden of neurologic diseases and the need for reallocating efforts and resources to cure them. The value of treatment project of the EBC and EAN has outlined ways how to improve the treatment of brain diseases.6, 7 Such efforts need to be set in place now. Health research must be much better and more intensively focused on basic and clinical neurosciences and resources concentrated to rapidly develop appropriate and effective prevention and treatment of brain diseases.
For us as neurologists and for the European Academy of Neurology it is the appeal for a continued support of national societies to fight against regional disparities, promotion of basic and clinical neurologic research and continued education to train the next generation of neurologists so that they can successfully face this epidemic.
- Disease GBD, Injury I, Prevalence C. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016;388(10053):1545-1602.
- DALYs GBD, Collaborators H. Global, regional, and national disability-adjusted life-years (DALYs) for 315 diseases and injuries and healthy life expectancy (HALE), 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016;388(10053):1603-1658.
- Group GBDNDC. Global, regional, and national burden of neurological disorders during 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. The Lancet Neurology 2017;16(11):877-897.
- Murray C, Lopez A. The global burden of disease: a comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projected to 2020. Boston: Harvard School of Public Health, 1996.