Reliable Cut-Off Values for BPDAI Score to Assess Severity of Bullous Pemphigoid Activity Established

Researchers have established cut-off values for the Bullous Pemphigoid Disease Area Index (BPDAI) score that reliably define mild, moderate, and severe bullous pemphigoid. Findings from this study were published in The Journal of Dermatology.

Overall, the study included 285 patients with bullous pemphigoid who were enrolled in 50 European dermatology departments (mean age, 81.75±9.18 years). The study had 2 blinded investigators who recorded severity scores. An enzyme-linked immunosorbent assay (ELISA) was used to measure anti-BP180 and anti-BP230 antibodies, the presence of which characterizes the disease. Based on the 25th and 75th percentiles of the BPDAI score, the investigators calculated cut-off values to represent mild, moderate, and severe subgroups.

In the study population, the median BPDAI activity was 37.5 points (range, 0-164). The cut-off values that corresponded with the first and third quartiles of the BPDAI score were 20 and 57. These values were used to define the severity of bullous pemphigoid disease: mild was up to and including19, moderate was from20 to 56 inclusive, and   severe was 57 and above.

In patients with 10 or fewer new blisters daily, the median BPDAI score was 26 (interquartile range [IQR], 17-45 points). In contrast, the median BPDAI score in patients with more than 10 new blisters daily was 55 (IQR, 39-82 points). At baseline, the BPDAI intraclass correlation coefficient was 0.97, and it stayed above 0.90 as long as month 6.

There was a significant correlation between improvement of the BPDAI score with the absolute decrease of anti-BP180 ELISA value (Spearman’s rank, r=0.34; P <.0037). No correlation was observed between improvement of the BPDAI score with anti-BP230 antibodies (r=0.17, P =.15).

Limitations of this study included the advanced age and poor health of mostpatients and the relatively large number of patients who died or were lost to follow-up (n=98).

In spite of these limitations, the researchers suggest the study offers strong evidence that the BPDAI score can accurately assess bullous pemphigoid activity “both at the time of diagnosis and during disease course, which might help clinicians to adapt treatment to disease activity and to drive controlled therapeutic trials.”

Reference

Masmoudi W, Vaillant M, Vassileva S, et al. International validation of the Bullous Pemphigoid Disease Area Index severity score and calculation of cut-off values for defining mild, moderate and severe type of bullous pemphigoid. Published online October 17, 2020. Br J Dermatol. doi:10.1111/bjd.1961