Significant Racial Differences Observed in Bullous Pemphigoid Severity

Emily Cole, MD

A new investigation into bullous pemphigoid suggested that racial differences could influence disease activity in affected patients, which Black patients in particular scoring higher in the Bullous Pemphigoid Disease Area Index (BPDAI).

Bullous pemphigoid is a autoimmune blistering disease (AIBD) that has been characterized by the disruption of hemidesmosome, which could lead to disruption in sub-epidermal bullae, as well as erosions, urticarial plaques, and persistent pruritus.

The BPDAI is an objective tool that’s been consistently used to assess disease activity in patients with bullous pemphigoid, and is comprised of total activity score (BPDAI-TAS) summed fro individual erosion and blistering scores (BPDAI-EB), urticaria/erythema(BPDAI-UE), andmucosa(BP DAI-M).

The tool is also capable of assessing pruritis in the past 24 hours, week, and month.

Previous validation studies of the tool included inter-rater reliabilities for other blistering disease assessments, but only 1 study described patient demographics that included non-White patients.

An investigative team led by Emily Cole, MD, Emory University School of Medicine, noted that the department of dermatology at the university she and her colleagues work at manages a diverse group of patients with AIBD, many of whom, are African American.

Previously, the team described differences in disease severity and pruritis in Black patients with AIBD. For the present study, Cole and colleagues evaluated the effect of race and Fitzpatrick skin type on BPDAI activity and pruritis scores.

Initially, the team performed a retrospective chart review of patients with bullous pemphigoid who were seen at the Emory BPDAI clinic between January 2014 and August 2020.Both BPDAI scores and Fitzpatrick skin types were assigned by the provider at the time of the visit.

The team utilized 2-tailed Kruskal-Wallis and Fischer’s exact tests to report standard deviation and differences in observed variables as well as numerical and categorical covariates.

A total of 107 patients were included in the analyses, 54.2% of whom were female. The patient population was predominantly White (68.2%), with 31.8% being Black patients. Age and gender distribution did not differ across either group or Fitzpatrick skin types.

Among these patients, investigators observed that Black patients demonstrated higher levels of anti-VP180 IgG (71.9±75.5vs. 37.9±49.1)and anti-BP 230 IgG(45.6±59.0vs.16.9±31.2)and peripheral eosinophil counts (1136.1±1959.8vs.281.1±320.4,p=0.001).

Black patients also reported greater BPDAI pruritus scored than White patients, which included itch over the past 24 hours, week, and in total. These findings were mirrored in Fitzpatrick skin types.

Overall, Cole and colleagues believed the data suggested racial differences in disease activity in patients with bullous pemphigoid.

They also believed that the BPDAI may under-estimate overall disease severity in darker skin types.

“Future research should explore alternative tools to assess disease severity in patients with darker skin types,such as computer-based systems and other objective measurements of skin inflammation,” the team wrote.

The study, "The Effect of Race and Fitzpatrick Skin Type on Bullous Pemphigoid Disease Area Index (BPDAI) Scores," was published online in the British Journal of Dermatology.