Tetracyclines
To assess the association of oral tetracycline use and IBD, they compared more than 144,000 patients whose acne was managed with antibiotics with patients whose acne was managed without systemic medications. The patients had a mean age of 24.4; 34.7% were male, and 68.2% were White.
Compared with the patients who were not on systemic medications, there were no significant associations among those on oral tetracyclines, with an OR for incident IBD of 1 (95% CI, 0.82-1.22), an OR for incident CD of 1.09 (95% CI, 0.86-1.38), and an OR for UC of 0.78 (95% CI, 0.61-1.00).
Isotretinoin
To evaluate the association of isotretinoin and IBD, the researchers compared more than 11,000 patients treated with isotretinoin with two matched groups: patients with acne managed without systemic medications, and patients with acne managed with oral tetracyclines. The latter comparison was made to minimize potential confounding by acne severity. These patients had a mean age of 21.1; 49.5% were male, and 75.3% were White.
In the first comparison, compared with patients not treated with systemic medications, the OR for 1-year incidence of IBD among patients treated with isotretinoin was 1.29 (95% CI, 0.64-2.59), with an absolute risk difference of .036%. The ORs for CD and UC were 1.00 (95% CI, 0.45-2.23) and 1.27 (95% CI, .58-2.80), respectively.
And compared with the antibiotic-managed group, the OR for incident IBD among those on isotretinoin was 1.13 (95% CI, 0.57-2.21), with an absolute risk difference of .018%. The OR for CD was 1.00 (95% CI, 0.45-2.23). The OR for UC could not be accurately estimated because of an insufficient number of events in the tetracycline-treated group.
‘Challenging’ area of research
Researching acne treatments and the potential risk of IBD has been a methodologically “challenging topic to study” because of possible confounding and surveillance bias depending on study designs, Dr. Barbieri, director of the Brigham and Women’s Advanced Acne Therapeutics Clinic, said in an interview.
Dr. John S. Barbieri
Studies that have identified a potential association between isotretinoin and IBD often have not adequately controlled for prior antibiotic exposure, for instance. And other studies, including a retrospective cohort study also published recently in JAAD using the same TriNetX database, have found 6-month isotretinoin-related risks of IBD but no increased risk at 1 year or more of follow-up – a finding that suggests a role of surveillance bias, Dr. Barbieri said.
The follow-up period of 1 year in their new study was chosen to minimize the risk of such bias. “Since patients on isotretinoin are seen more often, and since there are historical concerns about isotretinoin and IBD, patients on isotretinoin may be more likely to be screened earlier and thus could be diagnosed sooner than those not on [the medication],” he said.
He and his coauthors considered similar potential bias in designing the no-acne cohort, choosing patients who had routine primary care visits without abnormal findings in order to “reduce potential for bias due to frequency of interaction with the health care system,” they noted in their paper. (Patients had no prior encounters for acne and no history of acne treatments.)
