The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score: validity, reliability and sensitivity in adult patients with atopic dermatitis

BACKGROUND: The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score is a recently developed scale for evaluation of severity of atopic dermatitis, constructed from the assessment of epidermal barrier function, and properties using noninvasive bioengineering methods and computer-assisted estimates of disease extent. The method has been validated for use in infants and children with atopic dermatitis and compared with a referent scoring system. OBJECTIVES: The aim of the present study was to test the validity, reliability and sensitivity of the OSAAD score as an objective tool for the assessment of the severity of atopic dermatitis in adult patients. METHODS: Thirty-two adult patients with atopic dermatitis were included in the study. To assess the validity of the OSAAD score we tested it against the Severity Scoring of Atopic Dermatitis (SCORAD) index of the European Task Force on Atopic Dermatitis as a referent clinical severity scale, and the serum levels of interleukin (IL)-16 as a laboratory variable for monitoring the activity of atopic dermatitis. Responsiveness to change was assessed in a longitudinal study comparing OSAAD, SCORAD and serum levels of IL-16 before and after treatment. To test the reliability of the OSAAD score we studied the interobserver variability of the score recorded by three independent board-certified dermatologists in 16 patients and compared it with SCORAD. RESULTS: We report a significant correlation between the OSAAD and the SCORAD index as an acknowledged referent severity scale. The OSAAD score correlated significantly with the serum levels of IL-16 in the acute stage of atopic dermatitis. In a longitudinal study, the OSAAD score decreased significantly, parallel with improvement of the skin findings and a significant decrease in the SCORAD score and IL-16 serum levels. We report improved interobserver variability for the OSAAD score compared with SCORAD. CONCLUSIONS: This is the first study validating the OSAAD score as a sensitive and reliable tool for the assessment of the severity of atopic dermatitis in adult patients.