ARTICLE IN BRIEF:
A new analysis found that while the prevalence and incidence of motor neuron disease remained low overall, the burden increased significantly between 1990 and 2016, in large part because of the growing and aging population, particularly in high-income countries. Neuromuscular specialists discuss the strains and challenges that presents to recruiting trainees to the subspecialty.
Although motor neuron diseases (MND) are rare, the physical and financial challenges they pose to patients and their families, as well as health care providers and systems, are tremendous. In a new analysis published online November 5 in the Lancet Neurology, study authors quantified the global prevalence, incidence, and disability that comes with MND.
While the prevalence and incidence remained low, the burden increased significantly between 1990 and 2016, in large part because of the growing and aging population, particularly in high-income countries, according to the study.
“These data indicate that in the next decades the burden of MND will continue to increase and indicate that the expensive health services needed for people with MND need to be adequately planned, particularly in Europe, US, and Australasia to cope with this rise,” study author Giancarlo Logroscino, MD, PhD, professor of neurology and director of the Center for Neurodegenerative Diseases and the Aging Brain at the University of Bari Aldo Moro, told Neurology Today.
When the general public thinks of neurological disease, they associate it with being fatal, said Clifton L. Gooch, MD, FAAN, professor and chair of neurology at the University of South Florida School of Medicine, who published a 2017 paper in Annals of Neurology on the burden of neurological diseases in the US. People may die from neurologic diseases eventually, Dr. Gooch said, “but many of these diseases are disabling, sometimes for many years” — an important factor some previous epidemiology studies have not included, he said.
Highlighting the gaps in resources of which those in the field are all too aware, the Lancet Neurology article raises important questions about the future, experts said. This paper includes a measure of lifetime disability, disability-adjusted life years (DALYs), to quantify the devastating burden that comes with MND, something policymakers and analyses often overlook.
In addition, neuromuscular specialists who were not involved in the analysis said the paper underscores the need for training more specialists trained in MND at a time when neurology in general and neuromuscular specialists in particular are projected to be in shorter supply in the future.
The Lancet Neurology paper examined epidemiology of all motor neuron diseases using data from the GBD, a comprehensive regional and global research program to study diseases burden directed by the Institute of Health Metrics and Evaluation at the University of Washington in Seattle. GBD assesses mortality and disability from major diseases, injuries, and risk factors across different populations located in 195 countries all around the world with the contribution of almost four thousand collaborators.
Dr. Logroscino and colleagues included motor neuron diseases affecting all ages in their data: amyotrophic lateral sclerosis, spinal muscular atrophy, hereditary spastic paraplegia, primary lateral sclerosis, progressive muscular atrophy, and pseudobulbar palsy. They assessed incidence, prevalence, and DALYs.
They found that in 2016 there were 330,000 individuals with MND in the world and almost 33,000 deaths due to MND with an average incidence of 0.78 (95 percent UI 0.71-0.86) per 100,000 person-years and age standardized prevalence of 4.5 per 100,000. Prevalence of MND was consistently higher in men than in women, with a ratio that did not change from estimates made in 1990. Prevalence was highest in North America (20.2, 95 percent UI 19.0-21.5), followed by Australasia (17.7, 16.2-19.2) and Western Europe (16.7, 15.3-18.1).
“Even with low frequency, MND is responsible for elevated mortality and disability because of the severity of the disease,” Dr. Logroscino told Neurology Today. “The prevalence increases up to age 80 and then suddenly declines with a slightly higher frequency in males. This confirms that MND is not a disease of young adults but at least in part is linked to aging as previous studies from Europe had already shown.” More than half of the deaths from MND were recorded in high-income countries: Europe, North America, and Australasia.
One limitation, Dr. Logroscino said, was that although there were data from 55 sources in seven world regions, there were large areas of the world (sub-Saharan Africa, Eastern Europe, South and Central Asia, Latin America) with little to no data on MND.
The Gaps in Resources
Matthew M. Harmelink, MD, an assistant professor of pediatric neurology and director of the pediatric neuromuscular program at the Medical College of Wisconsin, said the paper reflected “what many of us in the field know intrinsically but not empirically: the high disease burden despite the low prevalence and incidence of the diseases themselves, and the strain that puts on the system.”
As the population continues to age and the burden of these diseases grows, the shortage of specialists trained in MND, and of neurologists more generally, becomes more apparent, said Merit E. Cudkowicz, MD, MSc, Julieanne Dorn Professor of Neurology at Harvard Medical School and chief of the neurology service at Massachusetts General Hospital. “There is an urgency to attract and train young physicians and physician scientists to the field.”
In recent decades several factors have had an impact on the number of neuromuscular specialists, including slashed reimbursements for electromyography studies and less time spent on neuromuscular disease during training, Dr. Gooch told Neurology Today. “It is my strong impression, having been a residency director, a fellowship program director in neuromuscular disease, and now serving as chair, that we are currently experiencing a significant shortage of neuromuscular specialists, especially in academic centers,” he said.
Over the past few years, Dr. Gooch and his colleagues have found it increasingly challenging to find and hire neuromuscular specialists, he said.
One way to address this, noted Dr. Harmelink, is to expose trainees earlier to neuromuscular care, and to offer better mentorship programs connecting seasoned neurologists in the field with trainees to help them navigate the system and advocate for neuromuscular clinics.
The commentators all stressed the importance of multidisciplinary care for their MND patients. They also pointed to exciting advances in drug discovery and treatment in their field, ensuring patients will be living longer with MND.
Specifically in pediatric neuromuscular disorders, new therapies for spinal muscular atrophy (SMA) and other conditions are making a significant difference for patient lifespan, Dr. Harmelink said. These intensive treatments will require a lot more time from the providers, he explained, and from the support services around them, some of which will have to be created.
“The new and expensive treatments for the motor neuron diseases, for example, nusinersen for SMA and edaravone for ALS, and additional promising therapies expected to be approved in the next year or two will create additional strains,” said Eric J. Sorenson, MD, FAAN, professor of neurology at Mayo Clinic in Rochester, MN, and past president of the American Association of Neuromuscular & Electrodiagnostic Medicine.
“Because the treatments are very expensive and time-intensive, there are few local neurologists who will be willing to treat these patients. Those treated will need to be managed at tertiary care centers, which will create a considerable burden on those departments.” The reality, he said, is that most of the care provided to MND patients falls outside of neurology to physical therapists, social workers, respiratory therapists, speech pathologists, and others.
This is part of a conversation Dr. Harmelink said his institution is already having. “There's a lot more discussion with our team about how we grow and who we need on the team. We're looking at a lot more of the support structures but also education for the primary care providers who are now also caring for these patients long-term.”
The multidisciplinary care teams can also be an important resource for the treating clinicians, he added, helping treat or prevent the specialists' burnout.
Dr. Cudkowicz said: “Neuromuscular care physicians actually see lower burnout rates because of the combination of team-based care and integration of research and hope into the clinics. It is an exciting and hopeful field.”
“Despite these daunting challenges, there's still a lot we can do for our specialty,” said Dr. Gooch. “Neurologists could advocate for more federal investment in targeted translational research and therapeutic development; for increased reimbursement for neurology and neuromuscular medicine to levels that would actually pay for the time required to deliver complex patient care, which would also encourage more young people to join the field; and to create and fund more multidisciplinary care systems for MND patients.”
As both the National Institutes of Health and Centers for Medicare and Medicaid Services are integral to making these things happen, Dr. Gooch said, individual neurologists must band together to make their voices heard in Washington, DC, and become advocates for their specialty by participating in medical societies and advocacy organizations, both regionally and nationally.
Neurologists must engage as volunteers and leaders, Dr. Gooch stressed. “If neurologists are too busy to go to Capitol Hill, they can still donate money or other resources. Only in this way can we regain our seat at the table and influence future policies for the good of our patients.”
The Global Burden of Disease database (GBD) is funded by the Bill & Melinda Gates Foundation. The study authors reported no conflicts of interest. Dr. Sorenson receives research support through a grant from Cytokinetics for an ALS clinical trial. Dr. Gooch is a consultant in ALS drug development for Mitsubishi Tanabe Pharma America. Dr. Gooch also is the president-elect of the Association of University Professors of Neurology, treasurer of the American Neurological Association, and serves on the editorial board for Neurology, none of which are compensated positions apart from providing meeting travel/lodging expense and meeting meals. Dr. Harmelink disclosed he serves on the advisory board to Biogen, PTC, Avexis, and Sarepta; is a consultant to Biogen, on research grants from CureSMA, and has a clinic infrastructure Grant from the Muscular Dystrophy Association; has a nonfinancial research affiliation with Invitae Genetics; and is a consultant for Connected Research and Consulting, LLC.