This study aims to explore the reliability and validity of newly developed Investigator Global Assessments (IGAs) in scoring the severity of pemphigus. IGAs are simple 5-point scales ranging from clear - severe and are preferred by the FDA as endpoints in clinical trials.

This study aims to obtain statistical data regarding the inter-rater and intra-rater reliability of the IGAs, Pemphigus Disease Activity Index (PDAI) and Autoimmune Bullous Skin Disease Intensity Score (ABSIS) as well as the convergent validity of the IGAs with the PDAI and objective component of the ABSIS.

Photograph sets of pemphigus lesions will be gathered from the lead site and participant sites. They will be de-identified and printed in a two hardcopy booklets; the first containing 20 photo sets and the second containing 17 new photo sets and 3 repeat photo sets. In the first part of the study, 8 dermatologists will score 20 sets of photographs of pemphigus lesions (a mixture of skin and mucosal lesions), using the IGAs for pemphigus as well as the PDAI and ABSIS. The first booklet will be mailed to dermatologists and they will use the booklet to score each photo set and will submit their scores in a confidential online survey. In the second part of the study, the second booklet will be sent to dermatologists in the same manner 4 weeks later, and each dermatologist will score the photo sets using the same scoring tools. It is estimated that each scoring session will take two hours to complete. Data gathered here will allow for calculation of inter-rater reliability and intra-rater reliability of the IGAs and convergent validity of the IGAs with PDAI and ABSIS.

Later, a sub-study will occur to calculate minimal clinically important differences (MCID) for the IGAs and PDAI. This will involve scoring pemphigus severity of patients at Premier Specialists using PDAI and IGA scores and a Likert score to classify patients as improved, stable or deteriorated compared to previous visits.

Inclusion Criteria:

• Having pemphigus diagnosed by a qualified dermatologist
• Aged 18 or older at the time of photography

Exclusion Criteria:

• Those whose photographs are unable to be adequately de-identified

Patients of the special bullous clinic at the lead site's dermatology practice who have been diagnosed with pemphigus.