eczema area and severity index eczema area and severity index the eczema area and severity index (easi) is a tool for the measurement of severity of atopic dermatitis. it ranges from 0 (no eczema) to 72. eczema area and severity indexpurposemeasurement of severity of atopic dermatitis easi is one of the core outcome instruments recommended to be included in all clinical trials on atopic dermatitis.