Host – Dan Keller
Hello, and welcome to Episode Seventy-five of Multiple Sclerosis
Discovery, the podcast of the MS Discovery Forum. I’m Dan
Today's interview features Elaine Kingwell, a research associate
at the University of British Columbia in Canada. She and her
colleagues have gathered and recently published incidence and
prevalence figures for people with MS in the province. I spoke with
Dr. Kingwell at the ECTRIMS meeting in Barcelona in October to find
out the reason for the study and to explore the changing trends she
found and their significance.
Interviewer – Dan Keller
What prompted you to do this study?
Interviewee – Elaine Kingwell
In British Columbia, we know that Canada has got a high
incidence and prevalence rate of MS, but we don't actually have the
numbers, so we've been doing a lot of research on MS in British
Columbia for many, many years. But we don't have the incidence
numbers for BC, and also the prevalence is out of date – the
estimates that we have – so it really was time to get an idea on
how many people we have in BC. And also, we wanted to look at
change over time, and we have access to some amazing administrative
databases in BC and also had some algorithms that we could use that
have been validated, so that we could identify people with MS in
Why are these numbers important?
It's important for lots of different reasons. For instance, it's
important to monitor trends over time. We're able to do that in BC,
because we have data going back several years. And so, it's
important to see if populations are changing, so that we can get
some clues about whether environmental factors might be changing.
And also, for the prevalence estimates, it's important to know how
many people have MS in the province, so that healthcare planning
can be done wisely and resources.
How do you go about looking at this?
So as I mentioned, we did use the health administrative
databases in BC, which are big databases that collect data on the
whole population. A number of different databases were combined,
including hospital admissions and physician visits. It's all claims
data, so that when someone goes to see their physician, a billing
claim gets put in with their diagnosis. So we use these codes to
identify people with MS. And we basically estimated the number of
people with MS [over] several years – one year at a time – so that
we could look at change over time for prevalence. And we also
estimated the incidence, the number of new cases each year,
starting in '96 right up until 2008.
What did you find in terms of incidence and prevalence?
Well we found the incidence and prevalence are both high. The
incidence was around 7.8 per 100,000 per year, and the prevalence
was around 180 to 200 per 100,000 in 2008. So they were both high,
what is relatively high compared to other places in the world and
similar to rates that have been found in Europe, in Northern
Europe, and other parts of Canada, as well.
And the prevalence is increasing over time?
Yeah, we found that it increased quite significantly by about
4.7% per year, so a big increase. It also shifted in the
predominant age of people, so that the peak prevalence age was
around in the mid-40s in the 1990s, and it's now shifted up into
the mid-50s. So the population of people with MS is getting older
in BC. We also saw with incidence … quite differently, the
incidence was not changing over time, so it stayed relatively
stable; it did fluctuate as incidence always does. But over time,
on average, it stayed the same.
Are those two pieces combined—increasing prevalence and older
I don't know if any of it's good news. It means that we have an
older population that are probably requiring more care, as they get
older, for the MS, as well as, of course, comorbidities they may
have. So, it's certainly something that healthcare planners need to
be aware of. And we have an aging population, in general, in
Canada, as we do in other parts of the world, but we have a lot
more people with MS at an older age.
But doesn't that mean they're surviving longer?
That's the good news part, yeah. And it does mean that, because
we're not seeing a change in incidence, the most likely explanation
is that the survival is better. People are surviving longer with
MS. We're seeing an increase in survival for the whole population,
but we're also seeing an increase in survival for people with
What about the gender ratio in terms of prevalence but also in
terms of survival?
We're seeing a gradual increase in the number of women relative
to men in prevalence. That's most likely due to the fact that women
do survive longer than men, on average, of course that's highly
variable. But on average, they survive longer than men. And so, if
you've got an aging population and three-quarters of the people
with MS are women, then you're going to find the number of women
How did the socioeconomic status affect the findings?
Yeah, so we did actually look at socioeconomic status. It was
measured at the neighborhood level, so not the individual level.
It's linked into the databases by postal code. We did find that
there were more people with MS in the higher levels of
socioeconomic status, but the absolute differences were not that
great. And, when we looked at this, it was not linked or adjusted
for other factors. So there's so many things that can be attached
to socioeconomic status and, of course, age is one of them, and
your age is greatly related to whether you have MS or not. And so,
there are other possible explanations, so we don't put a lot of
emphasis on that. When we look at socioeconomic status, we really
think that you need to design a study specifically to look at
Could you look at the use of disease-modifying drugs according
to socioeconomic status?
We could, and we have actually looked at that in other studies.
Again, as a kind of an adjustment factor or something to bear in
mind when we're looking at lots of variables at once, we find
there's the same kind of trend that people in the higher levels
tend to be on drug more often. But again, the absolute numbers are
very small, and it could totally be related to age or other factors
that are not adjusted in.
Were the data there to be able to look at early initiation of
disease-modifying drugs and any effects it may have had?
Well for this particular study – in the incidence and prevalence
study – we looked at just whether people had ever had drug. We
looked at the incident population to see if they'd had it in the
last three years or so—that's the three years from their first
claim, which is close to when they're first diagnosed or recognized
as having MS. And for the prevalent population, we looked at
whether they'd ever had MS. So we were able to tell that about a
third of the cases had had a disease-modifying drug. And this study
did start way back in the early 90s and then mid-90s for the
incidence cases. So, you would expect it to be a lower rate because
the drugs were just starting to become available in the mid-90s. So
we didn't look at the actual start date of the drug for this
particular study; we certainly are able to look at that because we
have access to the databases to look at those kinds of questions,
and we are looking at those kinds of questions in other
Can you put your findings in context to other studies at other
latitudes, locals, healthcare systems?
Yeah, that's a complicated question. Certainly as studies are
similar to the findings from some other studies. In particular, in
Canada, there's been some very similar studies done in Manitoba and
Nova Scotia where we've used exactly the same algorithm that was
validated in those provinces led by Dr. Ruth Ann Marrie from the
University of Manitoba. So, we found that prevalence and incidence
estimates are very similar, and the findings and the change over
time are also very comparable. When we look at some of the other
countries, there are some similar findings in other places, but
they vary a lot. When it comes to latitude, of course, we didn't
have a big latitude gradient in our study; we were just looking in
BC, and most of the people in BC live in one area around they're
concentrated in the south of the province. But certainly there's a
lot of variation in findings. But in order to get a look at the
change over time, you really need to look within the same
population on more than one occasion rather than comparing between
populations over time. It's really difficult to make that
Do you have a particularly good situation in BC in that you can
link databases of diagnostic codes, physician visits,
hospitalizations, pharmacy benefits, things like that that may not
exist in other places with a less coordinated system?
Yeah, definitely. We are in a situation where we have access to
some amazing databases. Many of the provinces in Canada have the
same or similar databases, so it is like that. We also have the
great situation that we have a clinical database in BC too where
we've been collecting data on MS patients over a very long period
of time. And we can link that data into the administrative
databases, so we have the depth of the clinical data that we can
link in the breadth of the administrative data, which has really
put us in a very strong position to look at these long-term
Is it pretty smooth to be able to delve into these databases, or
do you have any regulatory barriers like, in the US, we have all
these HIPAA things. Do you have a problem with de-identifying or
anything like that?
It's certainly not smooth. It can actually take us several years
to access this data. It's a long process. It's a lot of paperwork
for all of the reasons that…or some of the reasons you just
mentioned. The data is actually all handled through…when we're at
UBC, it's handled through Population Data BC, which is kind of the
center between the Ministry of Health and the databases. And they
strip all the identifiers off, so that by the time we receive any
data … we, of course, have to go through a lot of privacy concerns
and justification before we get any data sets. All the names and
the numbers are removed, so that we don't know who anybody is in
our database. Even when we're linking our clinical data, of course,
everything is completely anonymized by the time we work on anything
What kind of conclusions can you draw from what you've found so
One of the main conclusions, I think, is that the incident
population has leveled off, apparently, in BC. We started measuring
incidence in 1996, and it's possible there were changes in
incidence before that, but we can say that in the last 13 years –
up to 2008 – that the number of cases has leveled off, which is
good news it's not increasing. We also can say that the number of
prevalent cases, on the other hand, is increasing a lot, so that
the services need to be aware of that that there's going to be a
demand on the healthcare system, there already is. And also that
our results are very similar to as seen in other parts of Canada
The other main conclusion I would draw is that this study really
shows how you can utilize these types of databases and reliable
algorithms and ways of identifying people with MS in order to
monitor the number of people and also changes over time. And also
can give us some information about the people with MS and what
kinds of drugs they're taking because we're linked into the
PharmaNet databases, and we can do that too. So there's lots of
questions we can answer about the population in British
Thank you for listening to Episode Seventy-five of Multiple
Sclerosis Discovery. This podcast was produced by the MS Discovery
Forum, MSDF, the premier source of independent news and information
on MS research. MSDF’s executive editor is Carol Cruzan Morton.
Msdiscovery.org is part of the nonprofit Accelerated Cure Project
for Multiple Sclerosis. Robert McBurney is our President and CEO,
and Hollie Schmidt is Vice President of Scientific Operations.
Msdiscovery.org aims to focus attention on what is known and not
yet known about the causes of MS and related conditions, their
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For Multiple Sclerosis Discovery, I'm Dan Keller.