Bullous Pemphigoid Disease Area Index Pruritus, Activity, and Damage During Biologic Therapy in Bullous Pemphigoid: An International Dual-Center Study.

Biologic therapies targeting Type 2 inflammation are increasingly used in bullous pemphigoid, yet the relationship between pruritus and distinct disease domains remains incompletely defined. We conducted a retrospective international dual-center study of 25 patients with bullous pemphigoid treated with dupilumab, omalizumab, or tralokinumab. Bullous Pemphigoid Disease Area Index activity, damage, and pruritus were assessed at baseline and at Weeks 8, 16, 32, and 52. Mixed-effects models showed significant improvement in disease activity and pruritus from Week 8 onward, whereas damage showed a slower trajectory, becoming significant only at later timepoints. Pruritus improvement correlated with improvement in disease activity across all timepoints. Clinical response rates increased over follow-up. Although systemic corticosteroids were frequently used at treatment initiation and tapered thereafter, improvement was sustained during corticosteroid weaning. These findings support pruritus as a dynamic and clinically meaningful domain for monitoring treatment response, linked to inflammatory disease activity rather than residual damage.