Dan Keller 0:08
Welcome to this episode of Substantial Matters: Life and Science of Parkinson’s. I’m your host, Dan Keller. At the Parkinson’s Foundation, we want all people with Parkinson’s and their families to get the care and support they need. Better care starts with better research and leads to better lives. In this podcast series, we highlight the fruits of that research—the treatments and techniques that can help you live a better life now, as well as research that can bring a better tomorrow.
To best serve people with Parkinson’s and the health care providers who treat them, it’s essential to know how many people have the disease—for current treatment purposes and to allocate resources and funds for the future. But reliable figures for the prevalence of Parkinson’s in the U.S. population are lacking and have been based on outdated and possibly skewed estimates. In an effort to accurately capture these figures, the Parkinson’s Foundation has taken a leading role in determining the prevalence of PD and related conditions through the Parkinson’s Prevalence Project.
James Beck, the Foundation’s Chief Scientific Officer, says he believes the number of people living with Parkinson’s in the U.S. has been dramatically underestimated and does not represent the ethnic diversity of people affected by PD because of how we gathered older data. He explains how the Parkinson’s Prevalence Project is designed to give a clearer picture of PD in the country. First of all, what is prevalence, and what’s the goal of the project?
James Beck 1:53
Sure. Prevalence is just a fancy word for saying how many people have Parkinson’s today. What’s really surprising, I think, to many people with PD, is that they don’t appreciate that we really don’t know who has Parkinson’s today. It wasn’t until the efforts of the Foundation to better understand the prevalence of Parkinson’s that we had a firmer ground upon which to stand when we talk about who has PD today.
Dan Keller 2:15
The best evidence, or best numbers, were from quite a while ago until this project happened.
James Beck 2:22
That’s right. So probably the last study that really tried to capture the prevalence of who had Parkinson’s disease at one particular time was done in 1978. It was a really well-done study. It was a $15 million study—door-to-door epidemiology survey in a rural part of Mississippi called Copiah County, Mississippi, population right around 40,000 people.
And the goal of the study was to go door to door and identify people in a biracial community—equal Caucasians and African Americans—to see who had Parkinson’s disease. And as part of the process, they actually identified some people who hadn’t been diagnosed yet with PD.
You know, in 1978 Microsoft had 11 people in the company. It was a startup. In 1978, the black-and-white TV sat adjacent to your kitchen table. There was no social media. Our understanding of Parkinson’s disease has changed since 1978, and our ability to diagnose it—still clinically—but it has improved a lot.
So there really was an importance to be able to improve upon that and to take into account the fact that there were only 26 people identified as part of this study who had Parkinson’s disease in this rural county. Those numbers were never meant to be extrapolated to count the entire United States. Actually, the authors say so in the discussion of their paper—that it’s limited to this particular area.
Nevertheless, as people tend to do, they are given numbers and then extrapolate them to the entire United States. So for a rural county that identified 26 cases of Parkinson’s disease, it has been utilized to extrapolate to our entire country of roughly 330 million people that is ethnically and geographically diverse. And as a result, it has led many people to believe there are fewer people with Parkinson’s disease than there actually are.
If you hear numbers in the 500,000 to 600,000 range for people with PD in the U.S., that’s where those numbers are coming from. We as a community always knew in our gut that there were more people with Parkinson’s than that. One of the problems was the community was all over the place. Some people were more willing to accept these government numbers, others were more optimistic. We had settled on about a million people with Parkinson’s disease and convinced some other organizations that was about the right number.
Some of that was due to back-of-the-envelope calculations that I did a number of years ago. But I’m not an epidemiologist or statistician, and it was shaky ground. So when people would ask, we could give them numbers, but it was not substantial evidence in the way that would carry real weight.
So as part of an effort the Foundation is doing for the entire community, something we can all stand behind, we worked with a number of leading epidemiologists and movement disorder specialists who had access to rich but disparate datasets from different parts of the country. And we used these to create what’s called a meta-estimate. This meta-estimate was used to generate a revised estimate of who has Parkinson’s disease.
This is not the absolute last word, but it is a big step from where we were before. We worked with people who had administrative health care databases like Medicare, integrated health care systems like Kaiser Permanente in Northern California, and the Rochester Epidemiology Project at the Mayo Clinic in Olmsted County, Minnesota, where they effectively have every person diagnosed with PD in that county.
We pulled all this data together and used it to calculate prevalence across different age ranges—for example, ages 45–54 and 55–64. What was really interesting is that despite different methods of data collection, the numbers almost all lined up. They were slightly different, but essentially the same. So we had a lot of confidence in the estimate we generated.
As I mentioned, it’s not the final word. We still recognize variation in the United States. Some states have more people with PD than others. It doesn’t appear to be a geographic hot spot like you might see with cancer, but it is not evenly distributed either.
But the point is we now have a number upon which to speak as a community. That number is nearly 1 million people by 2020 who will have been diagnosed with Parkinson’s disease. That represents a floor—we can say with confidence at least this many people have PD, if not more. And part of that “if not more” comes from those who have not yet been diagnosed.
That remains a problem—getting accurate diagnosis quickly—and also reflects disparities in access to care, which is central to our mission: improving care and quality of life for everyone with PD.
Dan Keller 7:21
So I suppose knowing the more real number than you had before, and the distribution of the disease throughout the country—if there are geographic differences—would affect resource allocation and funding and things like that.
James Beck 7:38
Absolutely. These are important numbers upon which to build a case to talk to members of Congress, the federal government, and state governments to say Parkinson’s disease is bigger than we thought, and we have numbers upon which to stand to defend that case. We need to allocate more resources to it.
Even with imperfect studies estimating the economic burden of Parkinson’s, we are working with another organization to improve that number as well. But using these updated prevalence numbers with older cost estimates suggests almost $20 billion a year in societal costs.
The federal government, in turn, invests roughly $160–$180 million a year in Parkinson’s research—about 1% of the total cost. Even doubling or tripling that would make a tremendous difference for researchers and clinicians working on Parkinson’s disease.
It could help bring more scientists and clinicians into the field. It could also help insurance companies and other organizations prepare for increasing numbers of people with PD and ensure appropriate care services are available.
Dan Keller 9:04
Is that going to be the major benefit to people with Parkinson’s—that resources may be better allocated and more research will go on? Or are there other benefits you see right now?
James Beck 9:17
I think this is probably more of a policy benefit rather than a direct practical benefit, although there is strength in knowledge. For people with PD to know they are not alone and to have confidence in these numbers can be empowering. It allows them to be their own advocates for change.
Dan Keller 9:47
Now that you have good numbers in hand, do you have next steps as part of this project?
James Beck 9:52
Absolutely. Prevalence is one leg of a stool. Another important number is incidence—how many people are diagnosed each year. We have rough estimates of 40,000 to 60,000 per year, but we want a better estimate using the same datasets and researchers.
The other side is mortality—whether people with PD die sooner or live a full lifespan. This is difficult but important to understand so we can measure progress, including whether we are improving diagnosis rates or slowing disease progression with new therapies.
This study will be published in an open-access journal, NPJ Parkinson’s Disease, in partnership with Nature Research. Open access means anyone can download and read the article for free and review the data themselves.
Dan Keller 11:39
Good. Thank you.
Dan Keller 11:50
To find out more about the Parkinson’s Prevalence Project, including state-by-state estimates and other findings, go to parkinson.org and search “prevalence.” You can also call our toll-free helpline at 1-800-4PD-INFO to speak with PD information specialists.
You can also leave feedback at parkinson.org/feedback.
At the Parkinson’s Foundation, our mission is to help every person diagnosed with Parkinson’s live the best possible life today. We bring you a new episode every other week.
For more information, visit parkinson.org or call 1-800-473-4636.
Thank you for listening.
