Nearly one in 100 people in the United States have a form of inflammatory bowel disease, according to a new study led by the Crohn’s & Colitis Foundation. This number—touted by researchers as the clearest depiction to date of IBD in the United States—is one of the highest national rates in the world, according to researchers.
The INPUT (INcidence, Prevalence, Treatment, and OUTcomes in Patients with IBD) study found that IBD affects more than 0.7% of Americans, translating to approximately 721 cases per 100,000 people. “The numbers from our study and those from studies around the world mean two main things: The prevalence of IBD in the U.S. has been gradually increasing over the last decade, and thus the burden of caring for IBD is likely to increase as life expectancy increases,” said Andrés Hurtado-Lorenzo, PhD, the senior vice president of translational research and IBD ventures at the Crohn’s & Colitis Foundation, and a co-principal investigator of the INPUT study.
Of note, the study revealed significant variation by race, with white individuals having an IBD rate 21 times higher than Asian American, seven times higher than Black and six times higher than Hispanic individuals. According to the study team, it remains uncertain whether this difference is due to biased diagnosis or underlying biological variances; therefore, more research is needed to understand the reasons for these racial and ethnic differences in IBD prevalence. “Understanding the causes and implications of these racial and ethnic disparities is crucial for future research,” Dr. Hurtado-Lorenzo noted.
U.S. IBD Rates
To produce accurate estimates of IBD in the United States, the investigators analyzed four different health insurance claims data sets—including the national Medicare data, Medicaid data from five states and two commercial health insurance companies—and then calculated age-, sex- and race-specific estimates of IBD incidence and prevalence (Gastroenterology 2023 Jul 20. doi:10.1053/j.gastro.2023.07.003). These estimates were then standardized to the 2018 U.S. census.
Although it has been difficult to obtain U.S. population-level health data due to the fragmented nature of the healthcare system, the researchers maintained that these data establish the United States as having one of the highest prevalence rates of IBD in the world.
Commenting on the study, Ashwin Ananthakrishnan, MBBS, MPH, a physician investigator in gastroenterology at the Mass General Research Institute, and an associate professor of medicine at Harvard Medical School, in Boston, said the research team should be congratulated for their “phenomenal effort.”
“This is a very important study because it represents the first comprehensive attempt to merge different data sources, each with complementary strengths, to attempt to identify the burden of IBD in the United States,” Dr. Ananthakrishnan told Gastroenterology & Endoscopy News.
He agreed that more work is needed to understand the ethnic and racial differences found in the data, whether they are highlighting a biological basis of genetic or environmental factors or a reflection of lower access to care, he said. “There are also more nuances to that question—many studies have shown that immigrants have a higher risk in the second generation—so it is possible that racial/ethnic differences may be less striking once minority groups are made up of a larger fraction of second- or third-generation immigrants.”
IBD Around the World
Other countries with high incidence and prevalence rates of IBD comparable to those of the United States include Canada, the United Kingdom, Australia and several Western European countries. “Similar to our analysis, these countries have reported increasing prevalence of IBD over the past decade,” Dr. Hurtado-Lorenzo noted.
In comparison, many countries in Asia, Africa and South America have had traditionally lower rates of IBD. However, epidemiological evidence suggests that the incidence of IBD in these regions has been increasing gradually since 1990, he added, possibly due to changing environmental factors and Westernization of lifestyle (Lancet 2017;390[10114]:2769-2778; Int Health 2020;12[3]:222-230; United European Gastroenterol J 2022;10[10]:1113-1120). “IBD has attained a global scale, particularly in the newly industrialized nations that have undergone a cultural shift towards Westernization,” Dr. Hurtado-Lorenzo said.
He told Gastroenterology & Endoscopy News these epidemiological findings underscore the urgent need for new research focused on preventing IBD, incorporating personalized medicine to effectively address the multifactorial nature and high economic burden of these diseases. “The gradual increase in the prevalence of IBD in the U.S. calls for a comprehensive and patient-centered approach in clinical practice. This includes increased awareness, early diagnosis, personalized treatment, multidisciplinary care, cultural competence, and targeted efforts to improve awareness, diagnosis and treatment in diverse populations.”
To Dr. Ananthakrishnan, the research also demonstrates the need for dynamically estimating the prevalence, incidence, and racial and ethnic distribution of IBD “on a more real-time basis, perhaps at least once a decade.”
—Meg Barbor, MPH
Drs. Ananthakrishnan and Hurtado-Lorenzo reported no relevant financial disclosures.
This article is from the October 2023 print issue.