The prevalence of multiple sclerosis in Australia increased by 9% between 2010 and 2017, a study based on prescription data shows.
The rise in MS was likely due to increased longevity of people with the disease and improved diagnosis based on MRI rather than clinical symptoms, according to the researchers form the Menzies Institute for Medical Research, University of Tasmania.
In their analysis of PBS prescription data for disease modifying therapy (DMT) such as fingolimod, they calculated that the number of people with MS in Australia in 2017 was 25,607, a significant increase of 4324 on the estimate of 21,283 people with MS made in 2010.
Rates of MS increased by as much as 30% in states and territories such as South Australia and the ACT, whereas they remained stable in Victoria (up 3%) and Tasmania (5%)
The study also confirmed a strong correlation between MS rates and latitude, with prevalence almost double in Tasmania (138.7/100,000) compared to Queensland (74.6/100,000).
Overall the variation in MS prevalence was an increase of 3% per degree latitude.
PBS data for MS prescriptions 2017 (total 188,243):
|Glatiramer acetate (Copaxone)||19,688|
|Interferon beta 1-B (Betaferon)||7978|
|Interferon Beta 1-A (Avonex)||6793|
|Interferon beta 1-A (Rebif 44)||6026|
Writing in Multiple Sclerosis Journal, the researchers noted that the increase in prevalence was dependent on age, with little change in younger age groups (25-34 years) compared to significant increases of around 30% in the 35-49 years age group and an increase of over 40% in the over 70s.
There was also a 40% increase in the use of disease modifying therapy since 2010.
“One key reason to support our findings is the increased survival of people with MS,” they noted.
“The increase in prevalence may also reflect improvements in the diagnosis and reporting of MS, with modern diagnostic criteria enabling diagnosis on the basis of a single MRI rather than earlier clinical course-based criteria.”
However the figures may also reflect a true increase in prevalence of MS that might reflect changes in risk factors such as diet and obesity, the researchers said.
The study also showed that people with MS currently being treated with disease modifying therapy were almost a decade younger than those not being treated with disease modifying therapy (52 vs 61 years). The mean age at diagnosis was 41 years, with females representing 78% of the MS population.
The mean number of years since diagnosis was 15, with people currently treated with disease modifying therapy diagnosed 4 years earlier than those not using disease modifying therapy.