People who have been previously diagnosed with either celiac disease or inflammatory bowel disease (IBD) have an increased risk of being diagnosed with the other illness, according to new research.
The risk of IBD diagnosis is nearly 10 times higher for people with celiac disease, while the likelihood of a celiac diagnosis is nearly four times greater among people with IBD, the study found.
The study, “Association Between Inflammatory Bowel Diseases and Celiac Disease: A Systematic Review and Meta-Analysis,” was published in the journal Gastroenterology.
IBD and celiac disease are both autoimmune disorders, characterized by the patient’s immune system mistakenly attacking components of the digestive system.
In celiac disease, the intestine is attacked when the individual consumes gluten, a protein found in wheat, barley, and rye. For people with IBD, the immune system misidentifies and targets the microflora of the gut, causing inflammation.
It has long been thought that celiac disease and IBD were associated with one another in patients, but this had never been confirmed. To investigate this possible connection, a team led by researchers at McMaster University, in Canada, identified 9,791 studies published between 1978 and 2019, and analyzed 65. The majority of the studies were in Europe, followed by North America and Asia.
The researchers noted that Canada has one of the highest frequencies of IBD in the world. Both diseases share similar risk factors and their prevalence has increased in the past years.
“Clinicians have always suspected that IBD and celiac disease may be linked, however a clear association was never established,” Maria Ines Pinto-Sanchez, MD, a gastroenterologist, associate professor at McMaster University, and the first author of the study, said in a university news story.
From studies, the team analyzed data from a total of 13.6 million participants. The vast majority, 13.4 million, were healthy volunteers used as a control group. Their data were compared with that of 43,000 celiac patients and 166,000 people with IBD. The IBD patients included 39,000 with Crohn’s disease, 56,000 with ulcerative colitis, and 3,000 with indeterminate colitis.
The analysis found an increased risk for IBD among celiac patients, and a higher likelihood of celiac disease among people with IBD, compared with controls. Specifically, the relative risk for a person with celiac disease to develop IBD was 9.88 times higher than in controls. For a person with IBD, the relative risk of developing celiac disease was 3.96 times higher.
The team believes this newly confirmed association between the two conditions may inform future therapeutic approaches, since being diagnosed with both conditions may limit treatment options.
“Failure to diagnose one or the other condition could compromise proper response to available treatments,” Pinto-Sanchez said.
“It also raises questions on screening for the other disease in a patient already diagnosed with either IBD or celiac disease,” she added.
Clinicians will need to decide whether and when to screen for one disease in patients who have been diagnosed with the other. Ultimately, the researchers noted, clinicians will need to weigh important factors like the potential benefit to the patient and the cost-effectiveness of the tests.
“Our review has confirmed that there is a strong association between celiac disease and IBD, but at this time, it is unclear whether screening of IBD should be performed in celiac disease and vice versa,” said Elena Verdu, MD, PhD, professor of medicine at McMaster and the corresponding author of the study.
The team also looked at some biomarkers of the two diseases, but ultimately found their evidence to be of low certainty. The findings did indicate that the risk for anti-Saccharomyces antibodies, a biomarker for IBD, was elevated in celiac patients.
“More studies into the association of IBD and celiac disease are needed, as this could lead to screening and therapeutic interventions to improve patient outcomes,” Verdu concluded.