AD severity linked with IBD risk
The risk for new-onset inflammatory bowel disease appears to be higher in children and adults with AD, and the risk varies based on age, AD severity, and subtype of inflammatory bowel disease, the authors reported.
Overall, AD in children was associated with a 44% increased risk for IBD (adjusted hazard ratio (HR), 1.44; 95% confidence interval [CI], 1.31-1.58) compared with controls, the authors reported. They found a 74% increased risk for CD in children with AD compared with controls (HR, 1.74; 95% CI, 1.54-1.97). More severe AD was linked with increased risk for both IBD and CD.
AD did not appear to increase risk for UC in children, except those with severe AD (HR, 1.65; 95% CI, 1.02-2.67).
Overall, adults with AD had a 34% (HR, 1.34; 95% CI, 1.27-1.40) increased risk for IBD, a 36% (HR, 1.36; 95% CI, 1.26-1.47) increased risk for CD, and a 32% (HR, 1.32; 95% CI, 1.24-1.41) increased risk for UC, with risk increasing with increased AD severity.
Robust data with cautionary note
“This study provides the most robust data to date on the association between IBD and AD. It provides clear evidence for an association that most dermatologists or primary care providers are not typically taught in training,” Kelly Scarberry, MD, assistant professor of dermatology at Case Western Reserve University in Cleveland, told this news organization. “I will be much more likely to pursue diagnostic workup in my AD patients who have GI complaints.”
Case Western Reserve University
Dr. Kelly Scarberry
However, AD severity was measured by proxy, added Dr. Scarberry, who was not involved in the study, and the study lacked important racial and ethnic data.
Lindsay C. Strowd, MD, associate professor of dermatology at Wake Forest University, Winston-Salem, N.C., also not involved in the study, said in an interview that she found the size of the cohort and the longitudinal data to be strengths of the study.
Wake Forest University
Dr. Lindsay C. Strowd
But, she added, the “lack of family IBD history, race and ethnicity, and comorbidities, are limitations, as is treatment exposure used as a proxy for disease severity, given that physician treatment practices differ.”
For Steven R. Feldman, MD, PhD, professor of dermatology at Wake Forest, “the most important conclusion, and it is a definitive finding, [is] that IBD is uncommon, even in patients with AD.
“The findings could be misinterpreted,” cautioned Dr. Feldman, who was not involved in the study. “While there is an increased relative risk, the absolute risk is small.” The study found that “the highest relative risk group is children with severe AD, who have a roughly fivefold increased risk for CD.” However, he added, the incidence rates of CD were 0.68 per 1,000 person-years in children with severe AD and 0.08 per 1,000 person-years in controls.
Wake Forest University
Dr. Steven R. Feldman
“Basically, because Crohn’s disease and IBD don’t happen very often, the modest increase in relative risk the investigators found doesn’t amount to much we’d have to worry about,” he said. “The findings do not show any need to screen patients with atopic dermatitis for IBD any more than we’d need to screen patients without atopic dermatitis.”
The increased relative risk “could be a clue to possible genetic connections between diseases,” he added. “But when we’re making clinical decisions, those decisions should be based on the absolute risk that some event may occur.”
Susan Massick, MD, dermatologist and associate professor at The Ohio State University in Columbus, who was not involved with the study, said in an interview, “We are still scratching the surface of the complexity of the immune and inflammatory pathways in AD and IBD.
The Ohio State Wexner Medical Center
Dr. Susan Massick
“It is important to remember that correlation does not mean causation,” Dr. Massick said. “It would be premature to draw direct conclusions based on this study alone.”
The authors recommend future related studies in more diverse populations.
Dr. Gelfand and two coauthors reported ties with Pfizer, which supported the study. Dr. Gelfand and three coauthors reported ties with other pharmaceutical companies. Dr. Maguiness, Dr. Scarberry, Dr. Strowd, and Dr. Massick reported having no relevant disclosures. Dr. Feldman reported ties with Pfizer and other pharmaceutical companies.
A version of this article appeared on Medscape.com.