Abstract
Janus kinase 1 (JAK1) inhibitors are effective for atopic dermatitis, but carry risks of adverse events. Dose reduction may mitigate these risks, although real-world evidence of dose reduction strategies is limited. This prospective, real-world study investigated JAK1 inhibitor dose reduction among 60 adults with controlled atopic dermatitis treated with abrocitinib or upadacitinib for ≥ 3 months. Doses were halved or administered every other day, as capsules cannot be split. Patients could resume their original dose if needed. The primary outcome was the proportion of patients maintaining the reduced dose at week 12. Secondary outcomes included physician- and patient-reported measures at baseline, and weeks 4, 8, and 12, analysed using linear mixed-effects models. At week 12, 80% (48/60) maintained the reduced dose. All outcomes remained within treat-to-target goals for atopic dermatitis at week 12, except for POEM (mean 8.87, 95% CI 7.43-10.31). While disease activity was significantly increased at week 8, no changes were seen at week 12. Absolute changes did not exceed the minimal clinically important difference. All 8 patients who resumed their initial dose regained disease control at week 12. In conclusion, JAK1 inhibitor dose reduction was feasible in 80% of patients without a clinically meaningful increase in disease activity.