JAK Inhibitors in Atopic Dermatitis: Does Weight Matter? A Real-World, Nationwide Retrospective Study: IL-AD (Italian Landscape Atopic Dermatitis)

Introduction: Janus kinase (JAK) inhibitors are effective systemic treatments for moderate-to-severe atopic dermatitis (AD), rapidly controlling symptoms and improving quality of life. However, the impact of body mass index (BMI) on therapeutic response remains unclear. Methods: This multicenter retrospective study analyzed data from 388 adult AD patients treated with upadacitinib, abrocitinib, or baricitinib across 25 Italian dermatology centers between May 2022 and July 2024. Patients were classified as overweight (BMI ≥ 25) or non-overweight (BMI < 25), with disease severity assessed using EASI, IGA, and Numerical Rating Scales (NRS) for pruritus and sleep disturbance over 104 weeks. The effect of different treatment dosages was also evaluated. Results: No significant BMI-related differences in clinical outcomes were noted at most timepoints. However, in the upadacitinib 15 mg group, non-overweight patients showed greater EASI and pruritus improvements at Week 4 (p = 0.037, p = 0.039), although these differences resolved subsequently. At Week 104, higher BMI modestly reduced EASI improvement (p = 0.045) in multivariable analysis. Conclusions: Treatment dosage consistently influenced clinical improvement regardless of BMI. These findings confirm the efficacy of JAK inhibitors across BMI categories, suggesting minimal short-term BMI influence but highlighting potential long-term considerations in overweight patients, emphasizing personalized dosing strategies and prolonged monitoring.