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

Bullous pemphigoid (BP) is an autoimmune blistering disease resulting in pruritus and cutaneous blistering. Longitudinal studies characterizing the disease course of patients with BP on conventional therapy are lacking. We sought to characterize the changes in disease activity and pruritus of patients with BP on standard-of-care treatments. We conducted a retrospective cohort study on patients with BP on standard-of-care therapy. Generalized Estimating Equations were used to estimate the mean and standard errors for Bullous Pemphigoid Disease Activity Index (BPDAI) total activity score, BPDAI pruritus component score, and anti-BP180 autoantibody levels (BP180) over time. A total of 80 patients with BP showed consistent reductions in BPDAI total activity score and BPDAI pruritus component score, with a nadir at 4 months. BP180 decreased over time, with the largest reductions at 6 and 9 months. Median partial/complete remission was at 6.7 months, with relapses at a median time of 15.9 months. Receiving operating characteristic analysis determined an optimal BPDAI total activity score cutoff of 3.3 to discriminate partial/complete remission incidence (area under the curve = 0.895, sensitivity = 0.844, specificity = 0.78). In conclusion, in patients with BP on standard-of-care therapy, a natural course of BPDAI total activity score and BPDAI pruritus component score over time was comprehensively projected. BPDAI ≤ 3.3 was associated with partial/complete remission. These results provide reference data to guide future clinical trial design for BP.