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Host – Dan Keller
Hello, and welcome to Episode Seventy-five of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
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 But we don't have the incidence numbers for BC, and also the prevalence is out of date – the estimates that we have – so it really was time to get an idea on how many people we have in BC.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 the databases.
MSDF
Why are these numbers important?
Dr. Kingwell
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.
MSDF
How do you go about looking at this?
Dr. Kingwell
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.
MSDF
What did you find in terms of incidence and prevalence?
Dr. Kingwell
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.
MSDF
And the prevalence is increasing over time?
Dr. Kingwell
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.
MSDF
Are those two pieces combined—increasing prevalence and older age—good news?
Dr. Kingwell
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.
MSDF
But doesn't that mean they're surviving longer?
Dr. Kingwell
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 MS.
MSDF
What about the gender ratio in terms of prevalence but also in terms of survival?
Dr. Kingwell
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 are increasing.
MSDF
How did the socioeconomic status affect the findings?
Dr. Kingwell
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 that.
MSDF
Could you look at the use of disease-modifying drugs according to socioeconomic status?
Dr. Kingwell
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.
MSDF
Were the data there to be able to look at early initiation of disease-modifying drugs and any effects it may have had?
Dr. Kingwell
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 studies.
MSDF
Can you put your findings in context to other studies at other latitudes, locals, healthcare systems?
Dr. Kingwell
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 comparison.
MSDF
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?
Dr. Kingwell
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 followup studies.
MSDF
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?
Dr. Kingwell
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 like that.
MSDF
What kind of conclusions can you draw from what you've found so far?
Dr. Kingwell
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 and comparable.
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 Columbia.
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MSDF
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 pathological mechanisms, and potential ways to intervene. By communicating this information in a way that builds bridges among different disciplines, we hope to open new routes toward significant clinical advances.
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For Multiple Sclerosis Discovery, I'm Dan Keller.
