Nonalcoholic fatty liver disease (NAFLD) in patients with inflammatory bowel disease (IBD) is associated with worse outcomes, and that relationship may be influenced by nonmetabolic factors. That is the conclusion of a new nationwide database analysis. NAFLD is common in IBD, with an estimated prevalence of 27%-32%.
Dr. Shaya Noorian
Previous, smaller studies showed possible links between NAFLD and a history of IBD surgery, IBD disease activity, and metabolic factors, “but none of the studies looked at it on the scale that we did, and our study was more focused on outcomes than simply examining factors associated with both NAFLD and IBD,” Shaya Noorian, MD, of UCLA Medical Center in Los Angeles, said in an interview. Dr. Noorian presented the research at the annual congress of the Crohn’s & Colitis Foundation and the American Gastroenterological Association.
Dr. Noorian and colleagues found higher rates of hospital readmission, longer hospitalization, and higher costs, but not higher rates of death among patients with both Crohn’s disease or ulcerative colitis and NAFLD. The researchers analyzed data from patients in the Nationwide Readmissions Database (2016-2017), using ICD-10 codes to identify patients with IBD and NAFLD, along with propensity-matched controls. The study included 3,655 with Crohn’s disease and NAFLD and 7,482 without, and there were 2,026 with ulcerative colitis and NAFLD 4,094 without.
IBD hospital readmission rates were higher with comorbid NAFLD in Crohn’s disease (hazard ratio, 1.98; 95% confidence interval, 1.8-2.17; P < .001) and ulcerative colitis (HR, 1.97; 95% CI, 1.67-2.32; P < .001). Comorbid NAFLD was associated with additional length of stay Crohn’s disease (0.74 days; 95% CI, 0.29-1.18; P < .01) and ulcerative colitis (0.84 days; 0.32-1.35, respectively; P < .01), and there was additional cost of care with both Crohn’s disease ($7,766; 95% CI, $2,693-$12,839; P < .01) and ulcerative colitis ($11,496; 95% CI, $4,361-$18,631; P < .01).
Kaplan Meier curves for IBD readmission-free survival versus days since discharge showed clear separation in both Crohn’s disease and ulcerative colitis among patients with versus those without NAFLD.
Although evidence points to nonmetabolic factors being involved, metabolic factors such as obesity and diabetes are likely important as well. “We still do recognize that it’s very likely that these metabolic factors play a role in developing NAFLD in IBD. I think the fact that there are worse outcomes in patients with NAFLD supports the fact that we should do our best to control the metabolic factors like diabetes, obesity, et cetera. We don’t want to minimize that aspect of it. But I think the fact that there were still worse outcomes after adjusting for metabolic factors emphasizes the importance of researching these factors further to see which ones are the main contributors. If we can find the main contributor, whether that’s medication, IBD disease burden, or history of surgery, perhaps we can use that information to prevent development or progression of NAFLD,” said Dr. Noorian.
“Historical reports have examined the relationship between Crohn’s disease and NAFLD. The currently study included both Crohn’s and ulcerative colitis, thus impressively demonstrating the importance of this interaction across IBD,” said Matthew Ciorba, MD, director of the IBD Center at Washington University in St. Louis, who attended the session.
Dr. Matthew Ciorba
“This is the largest study to date, and the signal is very clear. It really does underscore the need [to study not just how] medications and other factors influence the clinical syndrome, but how it happens mechanistically. There are a multitude of metabolic interactions going on between the gut and liver. We need to understand this better – not just at the systemic level, but at the enterohepatic circulation level,” said Dr. Ciorba.
Possible mechanisms include liver toxicity due to medication, IBD-associated inflammation, or changes to gut bacteria, according to Dr. Noorian.
The study also brings to light something that could become an emerging problem. “In the past, Crohn’s patients were oftentimes thin because their Crohn’s disease wasn’t well treated. They were taking steroids all the time, so they had fat redistribution, including to the liver. Now we see IBD patients who are obese, and most are not underweight. It has become a compounding problem at this point with both conditions contributing to morbidity,” said Dr. Ciorba.
The study had no source of funding. Dr. Noorian and Dr. Ciorba have no relevant financial disclosures.