Real-world claims data quantify a side effect dermatologists are already seeing.
Adults with atopic dermatitis who start a Janus kinase inhibitor are more than twice as likely to develop acne within six months as those treated with Th2 cytokine inhibitors, according to a new study.
Findings from the large real-world US-based study put numbers on a risk long suggested by clinical trials and reinforced acne as a class effect clinicians should be prepared for, educate patients about and manage early.
The results were published as a research letter in JAMA Dermatology.
“In this cohort study, we found an increased risk of acne, but not folliculitis or rosacea, among patients starting a JAK inhibitor for AD treatment,” the researchers wrote.
“Findings are representative of US clinical practice but included no data on high-dose JAK inhibitor use or AD severity.
“In conclusion, physicians and patients should consider that starting low-dose JAK inhibitors may increase the risk of acne.”
Using the multiyear ADVANCES sequential monitoring system, investigators analysed longitudinal commercial claims data claims from January 2017 to May 2024.
The cohort included patients aged 18 years and over with atopic dermatitis who initiated either a JAK inhibitor (upadacitinib or abrocitinib) or a Th2 cytokine inhibitor (dupilumab or tralokinumab).
Patients with prior acne, other systemic immunomodulator use, immunocompromising conditions or non-AD indications were excluded to isolate treatment-associated risk. Propensity score matching balanced baseline characteristics, and follow-up extended for 180 days after treatment initiation.
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In total, 2744 JAK inhibitor users with a mean age of 42.6 years were compared with 27,440 Th2 cytokine inhibitor users with a mean age of 43.3 years.
Most patients (95.5%) started upadacitinib at the 15mg dose, and most (85.1%) started abrocitinib at the 100mg dose. Few patients increased their starting dose during follow-up.
Over six months, acne was newly diagnosed in 4.93% of patients starting a JAK inhibitor compared with 1.96% of those starting a Th2 cytokine inhibitor, translating to a relative risk of 2.51.
This was consistent across age and sex strata, with the highest absolute risk observed in women and in patients aged 25 to 30 years.
Importantly for differential diagnosis, this elevated risk appeared specific to acne. Rates of folliculitis and rosacea hovered around 2% at six months and did not differ meaningfully between treatment groups.
Within-class comparisons also showed no statistically meaningful differences between upadacitinib and abrocitinib or between dupilumab and tralokinumab.
When prior dupilumab use was allowed, the acne risk associated with JAK inhibitors became even more pronounced, suggesting that this effect persisted in real-world sequencing scenarios.
