Predictive factors for treatment responses to baricitinib in severe alopecia areata: A retrospective, multivariate analysis of 70 cases from a single center

Alopecia areata (AA) is a chronic, autoimmune skin disease characterized by non-scarring hair loss. Baricitinib, a Janus kinase inhibitor (JAKi), prevents hair loss and promotes hair regrowth by inhibiting the inflammatory Janus kinase-signal transducer and activator of transcription (JAK–STAT) signaling pathway involved in cytotoxic T cell responses targeting hair follicles. The introduction of JAKi has transformed treatment against severe AA. However, treatment responses to JAKi are highly variable among patients, and the predictors of responsiveness remain insufficiently elucidated. This study aimed to identify independent predictive factors for the efficacy of baricitinib in patients with severe AA using multivariate analyses. A retrospective study was conducted on 70 severe AA patients who started baricitinib treatment at Tohoku University Hospital between July 2022 and August 2023. The primary outcome was the percentage of patients achieving a Severity of Alopecia Tool (SALT) score of ≤20 after 9 months of baricitinib treatment. Multivariate analysis assessed potential predictors of baricitinib treatment responses, including AA type, sex, age, disease duration, history of atopic dermatitis, intravenous methylprednisolone pulse (IVMP) therapy, and Clinician-Reported Outcome (ClinRO) measures for eyebrows and eyelashes. Achievement of a SALT score of ≤20 and SALT score improvement rates were used as objective variables in the multivariate analyses. Among the 70 patients completing 9 months of baricitinib treatment, 41% achieved a SALT score of ≤20. Multivariate analyses identified several independent predictors for positive outcomes, including shorter disease duration (≤4 years), history of IVMP, therapy SALT score of ≤95 at baricitinib initiation, and female sex. Further, we found differential response patterns based on AA type and sex. Specifically, AA type significantly influenced treatment responses, with ophiasis alopecia (OA) associated with the poorest improvement rate. In summary, the response to baricitinib in AA is significantly influenced by sex, AA type, disease duration, history of IVMP, and pre-treatment SALT score.