Assessing Disease Outcome Measures in Bullous Pemphigoid on Standard-of-Care Therapies

Abstract Bullous pemphigoid (BP) is an autoimmune blistering disease resulting in pruritus and cutaneous blistering. Longitudinal studies characterizing disease course of BP patients on conventional therapy are lacking. We sought to characterize changes in disease activity and pruritus of BP patients on standard-of-care treatments. We conducted a retrospective cohort study on patients with BP on standard-of-care therapy. Generalized Estimating Equations (GEE) were used to estimate the mean and standard errors for Bullous Pemphigoid Disease Activity Index (BPDAI) total activity score (TAS), pruritus component score (PCS), and anti-BP180 autoantibody levels (BP180) over time. Eighty patients with BP demonstrated consistent reductions in BPDAI-TAS and BPDAI-PCS with nadir of 4 months. BP180 decreased over time with largest reductions at 6 and 9 months. Median partial/complete (P/C) remission was 6.7 months with relapses at median time of 15.9 months. ROC analysis determined an optimal BPDAI-TAS cutoff of 3.3 to discriminate P/C remission incidence (AUC = 0.895, sensitivity 0.844, specificity 0.78). In conclusion, in BP patients on standard-of-care therapy, a natural course of BPDAI-TAS and BPDAI-PCS over time was comprehensively projected. BPDAI ≤3.3 was associated with P/C remission. These results provide reference data to guide future clinical trial design for BP.