BC researchers find disability progression
in MS is slower than previously reported
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Medical Update Memo
January 24, 2006
Researchers at the University of British Columbia have found
that disability progression in multiple sclerosis takes places
more slowly than reported in earlier studies. They
also reported that being male or being older at disease onset
are not associated with a worse disease outcome, challenging
other fundamental concepts about MS. The study, which
was funded in part by the MS Society of Canada, appeared
in the January 2006 issue of Neurology.
Determining how multiple sclerosis might progress following
its onset is difficult. To tackle the issue scientifically,
researchers undertake studies of large populations of people
with MS in what are known as natural history studies.
For this study at the University of British Columbia, Dr. Helen
Tremlett, Dr. Donald Paty and Dr. Virginia Devonshire used
the database from the four MS clinics in British Columbia to
ascertain a study population of people with definite MS and
symptom onset prior to July 1988. They looked at two
different inception points – clinical onset and date
This methodology enabled them to find a
group of 2,837 individuals who fulfilled the study criteria.
Slightly over 70 percent were female, 88 percent initially
had a relapsing course, the mean age at onset was slightly
over 30 years old and for 40 percent their symptoms at onset
were sensory in nature. On average, the individuals in this
group had their disability score measured every 1.1 years.
As reported in the January 2006 issue of Neurology, lead
investigator Dr. Tremlett and colleagues found that the British
Columbia MS population took a median 27.9 years to reach EDSS
6, which was substantially longer than the 15 years found in
an earlier London, Ontario study.
The researchers in both studies used the internationally recognized
Expanded Disability Status Scale (EDSS), which is a method
of quantifying disability using a scale from 0 to 10. At
EDSS 6, an individual would require a cane to walk.
By using date of birth as an inception point,
the researchers were also able to challenge two other concepts
widely believed about MS: that male sex and older age at onset
are associated with more rapid progression to disability.
The UBC study confirmed that while men progressed more rapidly
from onset than women, it also showed that both men and women
require a cane for mobility at about the same age. The
researchers concluded that female sex conveys little benefit
in that women are more likely to develop MS and at a younger
age, but that irreversible disability developed at a similar
age to men.
In terms of developing MS later in life,
Dr. Tremlett reported the study found an older age at onset
did not necessarily lead to a “gloomy” outlook.
Not only did those older at onset have a longer disease-free
period (prior to the development of MS), but they required
a cane at an older age than people who were younger at disease
onset. On average, someone with disease onset in his/her 20s
required a cane at age 55. This same level of disability
was reached at age 71 for those diagnosed at age 50 and older.
“By examining absolute age when this
level of disability occurs (requiring a cane for mobility),
we have a better understanding of the natural course of MS,”
Dr. Tremlett noted. Dr. Tremlett holds a Dr. Donald Paty
Career Development Award from the MS Society of Canada.
The study was funded in part by the MS Society.
“Natural history studies like this
are vital. Information gleaned from them can help guide
prognosis and facilitate decisions regarding initiation of
drug therapies,” added Dr. William J. McIlroy, MS Society
national medical advisor.
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