Gay men are more than twice as likely to develop inflammatory bowel disease (IBD) than heterosexual men when both populations engage in high-risk sexual activity, according to new research from the Digestive Health Research Institute at Case Western Reserve University and University Hospitals Cleveland Medical Center (UH).

The study was published this month in the peer-reviewed medical journal Gut.

“To our knowledge, this is the first large population-based study that demonstrates a higher prevalence of IBD in men who engage in high-risk same-sex sexual activity,” said Emad Mansoor, study lead author and assistant professor at the Case Western Reserve School of Medicine and UH. “Our study is expected to open a new field of research into gastrointestinal inflammatory conditions.”

“Studying the cause of IBD in this underrepresented patient population in comparison to other patient groups,” said Fabio Cominelli, corresponding study author, professor at the School of Medicine and chief scientific officer at UH, “will allow us to further investigate the cause of disease development in Crohn’s disease and ulcerative colitis patients and develop personalized precision medicine and treatment strategies, while also reducing stigma.”

The study’s impact is significant, as more than 7.1% of the United States population identifies as LGBTQIA+, an increase from 5.6% in 2020, according to Gallup.

The findings

The team evaluated self-reported data from patients treated at 58 healthcare organizations in the U.S. between 2002 and 2022.

The data showed that in patients with a diagnosis of high-risk same-sex sexual activity, 0.8% were diagnosed with Crohn’s disease and 1.26% with ulcerative colitis. These findings were compared to men who engage in high-risk heterosexual activity, of which, 0.49% had Crohn’s disease and 0.52% had ulcerative colitis.

High-risk sexual activity as defined in this study includes sexual contact without barrier protection as well as having multiple sexual partners.

The team also further analyzed the data in relation to Crohn’s disease and found men who engaged in high-risk same-sex sexual activity were more likely to have peri-anal disease including peri-anal abscess, rectal abscess and stricturing disease of the colon or small intestine. Among those with severe manifestations of ulcerative colitis, men who engaged in high-risk same-sex sexual activity were more likely to undergo partial colectomy.

The findings will be further evaluated by the team–including investigation into the potential role of the gut microbiome–during a long-term study that allows investigators to track participants over time.

Continuing research with NIH funding

The team will continue its research to better understand if and how LGBTQIA+ individuals are more susceptible to gastrointestinal disorders through funding awarded this year for the Cleveland Digestive Diseases Research Core Center (DDRCC).

The center recently received a $100,000 supplementary grant from the National Institutes of Health (NIH). It will allow the researchers to significantly expand the number of LGBTQIA+ patients included in the DDRCC’s biorepository core, which collects plasma, tissue and stool samples and gut microbiome analyses.

“This supplementary grant is an addition to our $1 million NIH grant funding that is running 2020 through 2025,” Cominelli said. “We are in the process of opening a new clinic dedicated to LGBTQ+ patients with the goal of improving access to healthcare. Our goal is to improve patient access and develop new therapies for gastrointestinal conditions.”