Imma Perfetto
Cosmos science journalist
People with multiple sclerosis can expect to live for another 45 years after their symptoms are diagnosed, up from just 17 years just 50 years ago.
A 15 year study of mortality in people with multiple sclerosis (MS) across New Zealand – the first such study in the southern hemisphere – has revealed that life expectancies have risen by almost three decades compared to 1969.
Unfortunately the life expectancy is still 7.2 years lower than the general New Zealand population.
“We’ve just published the first nationwide, multiple sclerosis mortality study in the southern hemisphere in the last 30 years,” lead author Dr Ruth Leadbetter, from the Department of Neurology at Wellington Regional Hospital and the New Zealand Brain Research Institute, told Cosmos.
“All the previous recent MS mortality studies that have been done have all been from people living in Europe and North America. We haven’t, until now, known what people with MS in the southern hemisphere’s life expectancy is.”
The findings are in the Journal of Neurology, Neurosurgery, and Psychiatry.
Multiple sclerosis is a chronic neurological disease that can occur at any age, but is often diagnosed between the ages of 20 and 40 years old.
Read more: Brain science: a new way of thinking is needed.
Co-author and Research Fellow at the Menzies Research Institute for Medical Research at the University of Tasmania, Professor Bruce Taylor, told Cosmos that while we don’t have that depth of data in Australia, the same trends are being seen here.
“We know that nationally the age of people with MS is going up in Australia, which would indicate that mortality rates are falling,” he says.
“We did a comprehensive review of MS in Greater Hobart in Tasmania and what we showed was that the standardised mortality rate of people with MS had fallen to one – which means it’s essentially the same as the general population.”
“People are dying with MS and not of MS, and their life expectancy, which we used to say was significantly reduced by seven or so years, is now about the same for men and women in Australia.”
Taylor says this is probably due to two important factors: the development of multidisciplinary care and the fact that Australia has had effective medications for multiple sclerosis for the last 27 years.
“We’ve been able to reduce the impact of MS attacks significantly and, as a consequence, we’ve slowed the rate of disability accumulation in people with MS,” he says.
“And people with MS are getting a lot better care than they were, we now have MS clinics and people get specialist care throughout the course of their MS.”
In multiple sclerosis, the body’s immune system attacks and damages fatty material – called myelin – that surrounds and protects nerve fibres in the brain, spinal cord, and optic nerves. The symptoms are diverse and unpredictable, depending on which part of the central nervous system is affected and to what degree.
There is no cure and no single cause for the disease, although it may arise from a combination of genetic, immunologic, and environmental factors.
Read more: Deciphering the cryptic codes of autoimmune disease.
Leadbetter, Taylor and colleagues analysed data from New Zealanders for 15 years following a comprehensive nationwide prevalence cohort collected in 2006. They examined the effect of factors such as sex, disease type at onset (relapsing vs progressive), and age at onset and diagnosis, on survival age and mortality rates.
They found that the median survival age for the multiple sclerosis cohort was 79.4 years, compared to 86.6 years for the age-matched and sex-matched general New Zealand population. The MS group had approximately twice the mortality risk of the general NZ population with a standardised mortality rate of 1.9.
The next steps for their research, Leadbetter says, are to look at the factors driving the life expectancy difference seen New Zealanders with multiple sclerosis.
“Our research plan is to look at the same group of people with MS and look specifically at the people that have died and what they have died of, and whether or not we can see trends,” she says.
“Basically, we want to find aspects of the disease that we can target to try to improve the life expectancies of New Zealanders, and people around the world, with multiple sclerosis.”