Initial validation of the product of the signs global assessment and body surface area in atopic dermatitis

Background: Current valid instruments that measure the signs of atopic dermatitis in clinical trials may not be suitable for clinical practice because of their complexity. The product of a clinician-derived 5-point signs global assessment and body surface area (SGA × BSA) may represent a simple approach to quickly assess the severity of signs in patients with atopic dermatitis in clinical practice. Objectives: Evaluate the basic measurement properties of the SGA × BSA. Methods: Retrospective chart review of patients with atopic dermatitis treated in an outpatient dermatology clinic at Oregon Health & Science University from 2015 to 2018 who had a recorded BSA and SGA. Results: We identified 138 patients completing 325 clinic visits. SGA × BSA demonstrated strong and statistically significant (P <.001) correlations with the Eczema Area and Severity Index (r = 0.91, n = 19), average daily pruritus (r = 0.71, n = 177), patient global assessment (r = 0.74, n = 170), and a derived global scale composed of the average of 4 signs rated between 0 and 3 (r = 0.77, n = 282). Acceptability, responsiveness, and floor or ceiling effects of the measure were deemed adequate. Severity banding was maximized at 1, 21, and 87 (κ = 0.4902). Limitations: The patient cohort was gathered exclusively from a tertiary care clinic setting in the Pacific Northwest and lacked ethnic diversity. Conclusions: The results from this study suggest that SGA × BSA is a valid and feasible instrument for atopic dermatitis signs in clinical practice.