684 Variability in Bullous Pemphigoid Disease Area Index Scoring in Patients of Color

The Bullous Pemphigoid Disease Area Index (BPDAI) is an objective measure with activity scoring divided into erosions/blisters, erythema/urticaria, and damage. Emory Autoimmune Blistering Disease (AIBD) Clinic treats many patients with darker skin tones and the erythema/urticaria component can be challenging in patients with darker skin. In this study, we explored the effect of Race and Fitzpatrick skin type (FST) on BPDAI total activity score (BPDAI-TAS) and pruritus component scores (BPDAI-PCS) based on a retrospective chart review of BP patients from 2014 to 2020. 107 patients were included in the analyses: most subjects were White (68.2%), followed by Black (31.8%). Although Black patients had higher BPDAI-TAS compared to White patients, this association was not significant (22.9±23.9 vs. 18.3±18.1; p=0.261). BPDAI erosions/blistering (BPDAI-EB) and damage (BPDAI-D) were higher in Black patients (20.2±23.9 vs. 11.7±15.0; p=0.028, and 4.5±3.3 vs. 1.5±2.4; p=0.000, respectively). In contrast, BPDAI urticaria/erythema (BPDAI-UE) was lower in Black patients (1.8±3.6 vs. 4.0±7.2; p=0.090). Similar findings were observed in BPDAI by FST: patients with FST V-VI demonstrated higher scores for BPDAI-TAS, BPDAI-EB, and BPDAI-D, but lower scores for BPDAI-UE. Black patients demonstrated higher levels of anti-BP180 IgG (71.9±75.5 vs. 37.9±49.1; p=0.009) while Black patients and FST V-VI reported greater BPDAI-PCS (19.4 ± 9.2 vs. 14.3 ± 9.2; p=0.024). This study demonstrates racial differences in relation to BP disease activity. Black patients have higher BPDAI-EB, pruritus scores and increased levels of autoantibodies. BPDAI-UE scores were lower in Black patients potentially from underappreciating the urticaria/erythema in darker skin. BPDAI-D is more common in darker skin patients, but it is not clear how this relates to disease activity. BPDAI needs to be interpreted carefully in the context of skin tone and future research may require alternative tools to capture disease severity in darker skin types.