Antibiotics, acne itself
Research on antibiotic use for acne and risk of IBD is scant, and the few studies that have been published show conflicting findings, Dr. Barbieri noted. In the meantime, studies and meta-analyses in the general medical literature – not involving acne – have identified an association between lifetime oral antibiotic exposure and IBD, he said.
While the results of the new study “are reassuring that oral tetracycline-class exposure for acne may not be associated with a significant absolute risk of inflammatory bowel disease, given the potential for antibiotic resistance and other antibiotic-associated complications, it remains important to be judicious” with their use in acne management, he and his coauthors wrote in the study.
The potential association between antibiotics for acne and IBD needs further study, preferably with longer follow-up duration, Dr. Barbieri said in the interview, but researchers are challenged by the lack of datasets with high-quality longitudinal data “beyond a few years of follow-up.”
The extent to which acne itself is associated with IBD is another area ripe for more research. Thus far, it seems that IBD and acne – and other chronic inflammatory skin diseases such as psoriasis – involve similar pathogenic pathways. “We know that in IBD Th17 and TNF immunologic pathways are important, so it’s not surprising that there may be associations,” he said.
In their paper, Dr. Barbieri and his coauthors emphasize, however, that the absolute risk difference between acne and IBD is small. It’s “unlikely that population level screening is warranted among patients with acne,” they wrote.
A second new study
The other study, also published recently in JAAD, used the same TriNetX research platform to identify approximately 77,000 patients with acne starting isotretinoin and matched them with patients starting oral antibiotics.
The investigators, Khalaf Kridin MD, PhD, and Ralf J. Ludwig, MD, of the Lübeck Institute of Experimental Dermatology, University of Lübeck (Germany), found that the lifetime risks (greater than 6 months) for patients on isotretinoin were not significantly elevated, compared with those on oral antibiotics for either CD (hazard ratio 1.05; 95% CI, 0.89-1.24, P = .583) or UC (HR, 1.13; 95% CI, 0.95-1.34; P = .162) They also looked at the risk of irritable bowel syndrome (IBS) and found a lower lifetime risk in the isotretinoin group.
In the short term, during the first 6 months after drug initiation, there was a significant, but slight increase in UC in the isotretinoin group. But this risk decreased to the level of the antibiotic group with longer follow up. “The absolute incidence rates [of IBD] and the risk difference of UC within the first 6 months are of limited clinical significance,” they wrote.
It may be, Dr. Weiss said in commenting on this study, “that isotretinoin unmasks an already-existing genetic tendency to UC early on in the course of treatment, but that it does not truly cause an increased incidence of any type of IBD.”
Both studies, said Dr. Barbieri, “add to an extensive body of literature that supports that isotretinoin is not associated with IBD.”
Dr. Barbieri had no disclosures for the study, for which Matthew T. Taylor served as first author. Coauthor Shawn Kwatra, MD, disclosed that he is an advisory board member/consultant for numerous pharmaceutical companies and has served as an investigator for several. Both are supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. The other authors had no disclosures. Dr. Kridin and Dr. Ludwig had no disclosures for their study. Dr. Weiss had no disclosures.