The Pemphigus Disease Area Index (PDAI) was adopted by an international consensus (Murrell et al., 2008) and validated in 2009. It scores the skin, scalp and mucous membranes separately and adds irreversible damage — marks left by healed lesions.
How it is calculated
Skin: 12 areas (ears, nose, rest of face, neck, chest, abdomen, back and buttocks, arms, hands, legs, feet, genitals), each 0/1/2/3/5/10 by number and size of erosions and blisters — up to 120.
Scalp: 0/1/2/3/4/10 — up to 10.
Mucosa: 12 sites (eyes, nose, buccal mucosa, hard and soft palate, upper and lower gingiva, tongue, floor of mouth, labial mucosa, posterior pharynx, anogenital), each 0/1/2/5/10 — up to 120.
Damage: post-inflammatory hyperpigmentation or erythema from healed lesions, 0/1 in the 12 skin areas and the scalp — up to 13.
PDAI = activity (0–250) + damage (0–13), total 0–263.
Pick an area on the body chart or in the table and score its most severe involvement; mark “damage” if marks of healed lesions remain. Unscored areas count as 0 — “Others — 0” fills them at once. The result prints on one A4 page.
Questions and answers
How does PDAI differ from ABSIS?
PDAI counts and sizes lesions in fixed areas and scores damage separately; ABSIS measures the involved skin area weighted by lesion type plus eating discomfort. Both are validated; PDAI has better inter-rater reliability.
Is damage part of the activity score?
No. The pemphigus category (Boulard 2016) is based on activity, 0–250; damage, 0–13, is added to the total PDAI.
References
Murrell DF, Dick S, Ahmed AR, et al. Consensus statement on definitions of disease, end points, and therapeutic response for pemphigus. J Am Acad Dermatol. 2008;58(6):1043–1046.
Rosenbach M, Murrell DF, Bystryn JC, et al. Reliability and convergent validity of two outcome instruments for pemphigus. J Invest Dermatol. 2009;129(10):2404–2410.
Boulard C, Duvert Lehembre S, Picard-Dahan C, et al. Calculation of cut-off values based on the Autoimmune Bullous Skin Disorder Intensity Score (ABSIS) and Pemphigus Disease Area Index (PDAI) pemphigus scoring systems for defining moderate, significant and extensive types of pemphigus. Br J Dermatol. 2016;175(1):142–149.
