Objectives: Clinical scores used to assess the severity of atopic dermatitis (AD) rely entirely on subjective criteria to evaluate the severity of lesions and the extent of involvement. The aim of this study was to develop an objective measure of AD severity by measuring stratum corneum (SC) functions and by using computer-assisted estimates of involved body surface areas (BSAs).
Design: Barrier function of the SC was assessed by measuring transepidermal water loss, and SC hydration was assessed by measuring capacitance. The extent of disease was assessed using a computer-assisted algorithm.
Patients: A total of 38 sequential volunteers aged 4 months to 18 years (25 girls, 13 boys) with mild to severe AD at a university outpatient pediatric dermatology clinic.
Main outcome measures: The computer-assisted method for estimating BSA was compared with estimates using the "rule of nines." The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score, derived from measurements of SC barrier function and SC hydration and normalized for extent of disease was compared with the Scoring Atopic Dermatitis (SCORAD) index.
Results: Measurements of epidermal permeability barrier function and SC hydration correlated with clinical estimates of disease severity. The computer-assisted measurements of the extent of disease correlated with estimates derived from the rule of nines. The OSAAD scores correlated with the currently used instrument for AD severity, the SCORAD index.
Conclusion: The OSAAD is a new AD severity score that avoids the pitfalls of currently used subjective scoring systems by using objective measures.