Kilian Eyerich

Background Baricitinib treatment in adults with moderate‐to‐severe atopic dermatitis (AD) has demonstrated rapid improvements in itch as well as AD sign severity and affected body surface area as assessed by the Eczema Area and Severity Index (EASI) total score, whether administered as monotherapy or in combination with topical corticosteroids (TCS). As EASI clinical signs differ in time course and associated antecedents, the effects of baricitinib on each individual clinical sign are of interest. Objectives In this post hoc analysis, we aimed to investigate the effects of baricitinib on individual EASI subscores, namely excoriation, oedema/papulation, erythema and lichenification, in both monotherapy and TCS combination therapy trials. Methods We analysed the percent change from baseline in individual EASI subscores from three phase‐III, double‐blind, 16‐week trials of baricitinib in monotherapy (BREEZE‐AD1/BREEZE‐AD2) and TCS combination therapy (BREEZE‐AD7) cohorts via mixed model repeated measures (MMRM). Results Baricitinib 4 mg showed rapid and sustained improvements in all four clinical signs in both cohorts. Significant effects emerged at week 1 for excoriation, oedema/papulation and erythema scores in monotherapy ( p < 0.001) and TCS combination therapy ( p < 0.001, p < 0.01, p < 0.001), plateaued at week 4, and remained significant versus placebo through week 16. The effect on lichenification scores also emerged early, at week 1 in monotherapy ( p < 0.05) and week 2 in combination therapy ( p < 0.001), with scores continuously improving without a clear plateau. Effect magnitude was highest in excoriation scores, exhibiting near‐maximal reduction in week 1 of monotherapy and remaining highest across all timepoints in combination therapy. Conclusions Rapid and sustained improvements were observed across clinical signs of inflammation and particularly on excoriation following baricitinib treatment. Our findings suggest that selective inhibition of janus kinases 1 and 2 leads to rapid and sustained control of skin inflammation, and that rapid reductions in itch translate into early disruption of the itch‐scratch cycle.