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Survival Rate is Up for Adults and Children with Neuromuscular Disorders, Canadian Study Reveals

Ana Pena, PhD avatar

by Ana Pena, PhD |

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Adults and children with neuromuscular disorders — including those with spinal muscular atrophy (SMA) — are living longer, according to a 12-year population-based study in Ontario, Canada.

The recent drop in mortality is likely due to the latest advances in the management of respiratory complications, newer technologies for lung hygiene and night ventilation along with more prompt access to specialized services.

In addition, even though the prevalence of neuromuscular disorders (NMDs) as a whole is rising, in adults and children with SMA the proportion of subjects with the disease tends to remain stable.

These findings come from the study “Trends in incidence, prevalence, and mortality of neuromuscular disease in Ontario, Canada: A population-based retrospective cohort study (2003-2014),” published recently in the journal PLOS ONE.

Understanding the incidence and impact of NMDs in the population is important to evaluate the burden those disorders represent to patients, their families and the healthcare system. It is useful to learn more about the natural history of these diseases, which are highly variable, as well as the effects of new management approaches. It also can be a valuable to source to inform healthcare policy.

Canadian researchers conducted a population-based estimate of NMDs’ trends regarding incidence, prevalence and mortality over time. To calculate those trends, they used the public health administrative database of the Canadian province of Ontario, spanning the period from 2003 to 2014.

A study of this type provides a comprehensive picture of the natural history of the disease at a population level, exceeding other study designs more prone to bias and variability (e.g., chart reviews, surveys, family histories).

The database used covered all residents of Ontario, a population of approximately 13 million during the study period.

The study primarily used data from individuals who were identified as having one NMD during a hospital stay, or a visit to the emergency department.

NMDs reported included amyotrophic lateral sclerosis (ALS)/motor neurone disease, cerebral palsy, Guillain-Barré syndrome, metabolic disorders, multiple sclerosis (MS), muscular dystrophy (MD), myasthenia gravis (MG), neuromuscular disorders (non-specific diagnoses), neuropathy, post-polio syndrome, spina bifida and spinal muscular atrophy (SMA).

Over the 12-year study period, the prevalence of NMDs in adults was 72.6 per 100,000 individuals, considering only those admitted to the hospital or an emergency department. If including those identified by a physician billing code, the estimates rose to 1,344 per 100,000 adults. Likewise, prevalence in children was 50 per 100,000 and 544 per 100,000 children, respectively.
The frequency of NMDs as a whole rose on average 8% per year for adults and 10% per year for children. Exceptions to this trend were ALS and SMA, for which prevalence remained unchanged for both adults and children.
Incidence — the number of newly diagnosed cases per period of time or population at risk — decreased by an average of 3% per year in adults, as opposed to children, for whom it kept generally stable.
In general, when considering all NMDs together, survival raised in adults and children. Mortality rate in adults dropped from 34.8% in 2003 to 24% in 2014, and in children from 7.9% in 2003 to 3% in 2014.
Accompanying this reduction in death frequency, was a more intensive use of palliative care. The proportion of those patients using palliative care increased from 9.9% in 2003 to 21.5% in 2014.
Moreover, despite NMDs being more frequent in older adults, its prevalence increased the most in younger adults 18 to 39 years old, supporting increased survival of children into adulthood.
The decline in incidence (the number of new cases) among adults at the same time prevalence (the total number of cases) increases, also is indicative of improved survival.
Researchers hypothesise several reasons for this improvement, including better monitoring of respiratory complications, newer technologies for lung hygiene and nocturnal ventilation, as well as more timely access to specialist services.

The team also noted that even though a reasonable proportion (61.8%) of adults and children received palliative care before death, further improvements in delivery and uptake of palliative care should be made.

In Canada, most palliative care services are provided at the hospital, which results in unequal access to these care units across the country. Other barriers to palliative care include poor family awareness, cost, age-appropriateness of services, and people’s perceptions about this type of care.

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