Dr Kaplan recaps his address on the global burden of inflammatory bowel disease and how incidence and prevalence are rising in developing nations while slowing in the Western world.

Gilaad Kaplan, MD, is a professor at the University of Calgary Cumming School of Medicine in Calgary, Alberta, Canada.

Transcript:

Hi, this is Dr. Gil Kaplan. I'm a gastroenterologist and epidemiologist from the University of Calgary. I'm here at DDW 2023 to talk to you about our research in the global epidemiology of inflammatory bowel disease.

IBD is a modern disease of modern times rooted in the industrialization and westernization of society. One of the questions that really fascinates me is how do we transition from a handful of cases a few hundred years ago to millions of people afflicted with this disease across the world today?

To answer that question, my research group has been studying the evolution of inflammatory bowel disease across 4 epidemiological stages. The first stage is called emergence, and this is in developing countries where the incidence of inflammatory bowel disease is very low, and then something happens in society, and there's a transition where all of a sudden incidence rates start to climb dramatically. And we call this the second stage acceleration in the incidence of inflammatory bowel disease.

But while incidence is rising, the prevalence, the number of people living with the disease, remains very low. However, after decades of rising incidence, we transition into the third epidemiological stage called compounding prevalence. And that's essentially because IBD is a disease of young individuals, mortality is very low. The prevalence, the number of people living with the disease continues to climb year, after year, after year.

And eventually there is going to be a stabilization of prevalence. We call this fourth stage of prevalence equilibrium, and that's because the IBD population with time does age in society. And there as incidence starts to approximate mortality, we'll start to see prevalence level off. Now, these are kind of hypothetical, theoretical, epidemiological concepts. What we are presenting this year at DDW in 2023 are some analytical models around each of these different epidemiological stages.

We've had an exciting opportunity to present one of our studies where we've synthesized over 450 population-based studies that have looked at the incidence or prevalence of inflammatory bowel disease in over 75 countries throughout the world, spanning from the 1930s all the way up to 2020.

And in analyzing all these data, some of the epidemiological trends that we've seen include the rapidly rising incidents of inflammatory bowel disease in early industrialized countries in the western world— North America, Europe, Australia, New Zealand, that we saw in the latter half of the 20th century. But at the turn of the 21st century, we've seen a paradigm shift. We're starting to see the incidence inflammatory bowel disease in these western countries start to stabilize. Around a coalescing incidence around 5 to 15 per 100,000 for both Crohn's disease and ulcerative colitis.

In contrast, we've seen newly industrialized countries in Asia, in Africa and Latin America, start to pivot into the second epidemiological stage where we see rapidly rising incidence in these countries all over the world. And this is really important because if the incidence of IBD and newly internationalized countries in Asian Latin America mirror the progression of inflammatory bowel disease in the western world during the 20th century, you can start to imagine what is the implications for societies like China or India that have populations of over a billion people.

Now, in countries like China and India, the prevalence still remains very low, compared to a country like Canada, the United States where we estimate the prevalence of inflammatory bowel disease in Canada is roughly 0.8% of the population. That means roughly about 300,000 people currently are living with IBD in Canada. And some of the research that we've also presented this year at DDW is forecasting what's going to happen to the prevalence of IBD as we go into the future in Canada.

And our forecasting models suggest that the prevalence of IBD in Canada is going to increase by roughly 2.4% per year over the next decade. And that means by 2030, 1% of the Canadian population is going to be having Crohn's disease or ulcerative colitis. That's roughly over 400,000 Canadians living with IBD. And the challenges that we have in a country like Canada and these compounding prevalence stage countries like Canada, the US, Europe, is we are seeing an influx in the volume of people that were diagnosed with inflammatory bowel disease. But the other issue is, it's not just the number of people, but the complexity of care is getting really difficult as well. The reason being, is that seniors with inflammatory bowel disease is the fastest growing demographic with living with IBD. And the reason why we're seeing so many people who are over the age of 65 have IBD is first, we still make new diagnoses in people who are older, but also our IBD population is aging. Somebody with Crohn's Disease who is diagnosed in the 1990s in their thirties is going to be 70 in 2030.

And that means that the types of clinics that we're going to be seeing over the next decade are going to see increasingly more older and more complex patients, and not only will have to manage their inflammatory bowel disease in the context of complications and their medications, but we'll have to do that in the context of age-related comorbidities like cardiovascular disease, diabetes, and cancer. It's just going to make our lives much more difficult.

But there is a little bit of hope, because this last stage is prevalence equilibrium, suggesting as we go forward in the next 10, 20, 30 years, prevalence should stabilize because incidence in most of these highly industrialized countries is stabilizing. And with the stable incidence we have projected with some mathematical models that prevalence will likely kind of level off around 1.5% of the population over the next few decades.

And this is probably the most exciting part of the research that we're doing, plus all this research is happening across DDW, is that we've done some models to show that if we can reduce the incidence by 1 or 2%, we can dramatically reduce prevalence over the next few decades. And that's why it's so important for us to prioritize preventative studies where we prevent actually new diagnosis and the incidence of inflammatory bowel disease in the future.

In the meantime, while we wait for those types of interventions to occur, health care systems across the world, including developing countries, newly industrialized countries in Asia and Latin America, and highly industrialized countries in the western world, need to prepare their health care systems for the changing demographics of their IBD populations as they transition across these different epidemiological stages in the evolution of IBD.